If you have secure boot enabled make sure you’re booting the UEFI option and not the raw USB medium. You’re looking for a UEFI entry from the flash drive
If you booted the raw usb drive you got the MBR partition table and non-efi bootloader with grub2
On fedora it’s one command
on Ubuntu you have a GUI for it
Before it’s too late it would also help to try gnome on xorg if that’s the DE you’re using. From my experience wayland is still not ready for nvidia
You could have just done a systemctl restart network-manager if your wifi driver took a dump
Basically everything that needs to be said has been said; you need a newer version for the newest hardware.
The only driver you need to install is the nvidia drivers, and there’s simple guides on howto do that, just make sure you’re reading an up to date howto and naturally for the correct distro.
A little tip when coming to linuxland. Change your mentality like this: you shouldn’t need to overthink and troubleshoot or install drivers, instead it’s the linux kernel that supports your hardware, all drivers are already built into the kernel (apart from nvidia).
Give Fedora, Manjaro or OpenSuse Tumbleweed a try.
EDIT: I realized the distro recommendations might be targeted towards more seasoned linux users, and I completely overlooked Mint.
It’s a wonderful distro for beginners, and while it’s not as bleeding edge as the aforementioned ones, it does provide the ability to upgrade the kernel and install nvidia drivers directly from the settings, no need to touch the terminal at all.
“Nvidia isn’t ready for wayland” you mean 
You are combining overpriced flaky hardware and newbie experience into one big pile of crap experience package.
Nvidia issues are given, its been like this for years thanks to nvidia. If your system were amd based, your experience would be hassle free in comparison, no additional configuration or hacks required.
On rhel-line based systems installing closed drivers is nearly hassle free operation of three steps.
Also since you have 9950x3d, why not use integrated gpu as a workaround to get your dgpu working? Thats what I did.
If you are using 10gbe port, switch to intel 2,5 gbe. This board comes with cheapass aqunatia controller that not well liked for good reason (firmware and drivers are not great). Still better that realtek though and even if intel 2,5 gbe controller is not without issues.
Regarding secure boot, there is zero reason to touch it at all if you are using any mature distribution. They use microsoft signed binary shim, which is trusted everywhere by default.
Don’t use Ubuntu 22.04. If you really want Ubuntu (I don’t, because I dislike Snaps and their proprietary nature), grab 25.04 or even 25.10 since you have the latest hardware. You definitely want Kernel 6.12+.
Usually Ubuntu Desktop is really simple to set up, but the hardware has to be supported. If it’s not, it quickly becomes a nightmare.
I use an AMD EPYC 8024P server CPU with no GPU (actually the motherboard probably has some sort of GPU so that stuff can boot, but it’s probably the ASpeed2600 integrated stuff - not entirely sure and didn’t bother, also doesn’t matter in this context).
Before you install, you really might want to boot into a live environment to test if it boots up.
I understand the rant though - most of us have been there at one time or another.
Tbh reading this thread I have a feeling the iGPU is the culprit here - either set the iGPU as default for now and use it primarily and only bring up te 5090 for compute workloads, or disable it entirely to force dGPU being the only available display method.
That’s fine, it’s not for everyone. Jumping in head first like this isn’t the best way to learn anyway. As an example I installed Windows 11 for the first time (I had stuck to Windows 10 previously and have been linux-only for a couple of years) on a Minisforum G7 Ti with nvidia 4070 laptop graphics and it literally took me like 4 days to get it working the way I wanted it to. It was also a frustrating experience.
I would guess that any frustrations you experience with Windows installs just feel normal, while frustrations with Linux are new and scary.
If you aren’t actually interested in learning about it, Linux is probably not for you.
Good luck! Although I hope newer AMD doesn’t need ACPI quirks.
I only looked at ACPI with Hackintosh and minor DSDT patching, and that took some time and details (had an Acer Intel 950GMA laptop that mostly was compatible). I looked into it again briefly, and reinstalled Linux 
(that SSDT stuff looks like a learning process with trial-and-error).
Somehow AAPL,ig-platform-id at 0900A53E looks good for Intel UHD 630, but 00009B3E for UHD 620, unless you have NUC in which case both UHD 630 and 620 can use 07009B3E. (all that’s macOS-specific/not related to this thread)
It’ll be cool to understand all that in detail eventually, but I need an OS in the meantime
I had the exact same cpu and gpu as you do and here’s what I did to get it set up properly for me today:
At this step, I got a working ubuntu but nvidia driver is not set up.
This driver doesn’t seem to work with gnome and I had to solve it in tty.
I hope this helps. Also I will update this if I had any issues.
Edit: fixed typo, version is 24.04.
Same hardware, 20.04?
Where do people get these outdated versions from?
Sorry 24.04, typo
Probably works on gnome xorg
I tried logging into gnome xorg but maybe I have to disable wayland in the config file altogether? Anyways, I’m good with lightdm so I don’t think I will bother with that until I have to.
I’m not sure where Ubuntu’s at, but Fedora 42 removed Xorg support hard; GNOME Xorg session can still start, but GDM log-in itself doesn’t work on Xorg. From the log-in screen I went to a TTY (Ctrl + Alt + F3), logged in, typed startx, and was in GNOME on Xorg fine 48.
I’ve heard lightdm works, but I find it extra since startx works (just a less-pretty log-in, but lockscreen still works fine).
this worries me. I have an EVGA classified card that’s super rare with the OG backplate which is still pushing pixels hard with no signs of giving up. Wayland was half developed for the card and then abandoned so I’ve always needed xorg for any non-buggy functionality
In the past I have had linux running on a Playstation, a decade old macbook, and now on brand new, cutting edge hardware (as of the last gen) and not once has it been the headache you describe. Perhaps the problem lies elsewhere…