I've considered this, but my branches don't generally live longer than a week and there isn't usually multiple engineers working on a codebase at once. Thankfully my team is smallish and the projects are either small maintenance items or greenfield. I'll look into where we can leverage it though!

This 100%

You need rebase instead.

Yep yep, that's what I do for my feature branches! ;)
Or, well, at least when I'm the only one working on them, anyway~

when it comes time to PR

Oh haha, I really doubt I need to worry about that; these are pretty community-specific features, I doubt the upstream project would even want them. I am concerned only with keeping my fork's main development branch up to date with the upstream's. Y'know, after I merge my custom features into it. There seem to be a bunch of intricate ways to do it (see the blogpost I linked), and I'm unsure if I should care about any of those, or if I can get away with just,, doing a normal merge.