This would likely only hurt the end user. Many use chromium-based browsers, so you're just driving those away.
You can detect Firefox, so you can do a superficial block in JS, but lemmy is such a simple site that you'd find it hard to find areas where there's actual differences between the browsers, those usually only come from complex pages like video calling
Same logo as on the left picture (bottom right corner) but rotated to align with the finger
I use it for everything, because I connected my external monitors through the eGPU. https://wiki.archlinux.org/title/PRIME has a few methods for running only selected applications via the eGPU, but I haven't tried them. Edit: See also https://wiki.archlinux.org/title/External_GPU#Xorg for eGPU specific setups.
Can confirm, I'm using a dock (from Razor) daily without problems. Hot switching doesn't work though, you need to restart X/your display manager to connect or disconnect the eGPU. I'd recommend the gswitch utility to configure the graphics card to be used (on X11). Haven't tested much on Wayland, but I know that at least Gnome (Wayland only) has trouble mixing eGPU and the internal display if that is important.
The main reason for Ubuntu against Debian is the packages. For Ubuntu, they're much newer, and with PPAs (launchpad.net), you can often get more and/or newer packages built by other users. For debian, good luck, you're stuck with old packages (which is the intent of Debian stable, but not nice as a user, that's for server)