Having a dream isn't wrong, but every business is difficult, and this one is already being run under by cheap Chinese prints.
It's still possible, but all the success I hear now is from people who have designed their own product and are fulfilling specific needs, like adapters for certain tools and such.
Etsy also just banned 3d prints of other people's design, so it's even harder to make money with those now.
You can still make money with your own designs on Etsy, and direct to people who need things, but now it's as much about the design of the items as the printing of them.
I suppose selling at a local market can still work, too, but it's a huge time sink. (Like any other job, I guess.)
That sounds like pretty much exactly what we did at my last job, and it worked pretty well IMO. The individual commits in a PR didn't ever matter. I don't even think we used them for code review, except if it came up for review a second time after rework. In that case, we were able to just look at the new commit to see if the right changes were made.
And we definitely avoided basing off each other's branches. We had to do it a few times. The only times it went well was when the intent was to merge the child branch into the feature branch. If they were actually separate tickets (and the second relied on the first) it was generally chaotic. But sometimes, it was just necessary.