Will pihole 5.1 work with the latest version of PopOS!; 20.04 ?
Officially supported - no.
But since it is based now on a supported OS, there is a fair chance it'll work.
It remains for you to try and find out, however. Other community members may be able to share their experience should you encounter difficulties. And they may also benefit from you sharing yours in return.
Where can I post about this issue to get more feedback?
Do you experience issues already?
You can post here in the Forum in Help/Community Help
When I uploaded to PopOS! like, 19 or something before, Pihole wouldn't install/work, so I had to redo the whole box because I really needed Pihole. I had to reinstall and downgrade my PopOS! and then reinstall Pihole. It was a real pain in the ass. I wanted confirmation... should I just install Ubuntu on my System76 and forget PopOS!?
You could wait if some else does report successful installation/upgrade of v5.1.1 or you the one doing it first
Using Ubuntu might be the more hassle free way. I would way it depends on how much you want/need PopOs over Ubuntu.
Well System76 documentation says that PopOS! is more friendly with their hardware. However, I'm assuming Ubuntu should work just as well on their hardware.
Is Pihole set to work on the latest version of Ubuntu?
I could just install Ubuntu and be done with it, but I'll have to redo Plex, which is the biggest pain.
You could also install pihole in a docker and keep PopOS...
Officially supported are Ubuntu 16,18,20.
Ubuntu 20.04 LTS <-- I see that as the latest version of Ubuntu.
I should just wipe the System76 and install Ubuntu. I just don't know what I'd be missing or doing to hurt me since the thing came with PopOS! already installed.