I've been using Ubuntu for about 3, years now on the desktop and I don't know what you're talking about. Where exactly is that prompt?
And they're not hiding updates behind pro, it's just extra on top of the updates you'd get on other distros.
Does what? Sign up for ubuntu pro? For that you just need to go to their website and register. For the homelab stuff you could start small - maybe a linux nas with a few VMs for a pihole or something.
Funny Gentoo actually was my gateway to arch. Loved the customizability of Gentoo and the rolling release model.
But building Chrome and Firefox (I needed both for work reasons sometimes) every update was the nail in the coffin. Switched to Arch and didn't miss a thing.