I don’t use nVidia stuff and I don’t use flatpak.
From their site, they say do this first,
You should be able to install from the web at flathub since you are using an Ubuntu variant. Click the install button:
From Leinardi’s githlab:
flatpak --user remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
flatpak --user install flathub com.leinardi.gwe
flatpak update # needed to be sure to have the latest org.freedesktop.Platform.GL.nvidia
You are having issues with the NV libraries so that update step may be what is needed. IT looks like you did not run that step.
Then you can run it with
flatpak run com.leinardi.gwe
Also note that