I have 2 ssd in my system and I want to raid 0 them with lvm and encrypt them whilst having the boot and luks header separate.
I do something similar with Pop_OS (just with RAID1 instead). I followed these guides:
Generally I followed the first guide, but since I was installing Pop_OS 22.04, there are times where you need to jump the second guide to get the right settings (like the fstab mount options).
You can do RAID0 with this by just converting BTRFS to RAID0 (keep metadata as RAID1):
btrfs balance start -dconvert=raid0 -mconvert=raid1 /mnt
Oh and just for a tip, so long as you have Ethernet or can connect to WiFi when you boot into the Pop_OS installer, you can bring up the guides in Firefox which makes things a little easier.