Not necessarily. For all of these cases, Debian, Ubuntu, Pro, the community and Canonical are package maintainers. Implementing patches means means one of: grabbing a patch from upstream and applying it to a package (least work, no upstream contribution); deriving a patch for the package from the latest upstream source (more work, no upstream contribution); creating a fix that doesn’t exist upstream and applying it to the package (most work, possible upstream contribution). I don’t know what their internal process is for this last case but I imagine they publish fixes. I’ve definitely seen Canonical upstreaming bug fixes in GNOME, because that’s where I have been paying attention to at some point in time. If you consider submitting such patches upstream as actively involved in project development, then they are actively involved. I probably wouldn’t consider that active involvement just like I don’t consider myself actively involved when I submit a bug fix to some project.
Ignore the noise and go with Ubuntu LTS. When you get comfortable with that, you could try Debian.
You could play it backwards too. Try Debian, if you can’t get it to do what you want, wipe and do Ubuntu LTS. But I do not recommend this path if you have no idea what you’re doing. People underestimate how difficult it is to do simple things when you don’t know how to, no matter how trivial.