Back with newsgroups the general rule was to go from general to specific. You start with a general discussion group and when discussions about video games get annoying you create a games group. If then there are too many Baldur’s Gate discussions you create BG. If they are dominated by Baldur’s Gate 3 you create a Baldur’s Gate 3 group. If everyone is fawning over Withers you create a Withers group which of course will be flooded with discussion about the Withers’ tits mod, which shall get its own group.
Meaning you should create a group when demand is there and not the other way around.
At this moment, there are at least a few manual hobbies that could coexist on the same community
They don’t have to be as interested in the other ones as their own niche, but at least they can share space and activity.
You could potentially have an “outdoor hobbies” with fishing, camping, animal trapping etc.
You kind of already see this when all of those hobbies can post to !imadethis@lemm.ee