alt Hacker NewsThat sounds like a nice improvement, just like many other aspects of jj!
Tools should adapt to us and not the other way around, but if you are stuck with git, there's a slightly different workflow that supports your use case: detached head. Whenever I check out branches that I don't intend on committing to directly, I checkout e.g. origin/main. This can be checked out in many worktrees. I actually find it more ergonomic and did this before using worktrees: there are no extra steps in keeping a local main pointer up to date.
The detached head is what I meant with keeping it on the branch while not keeping it on the branch.
The complication comes from trying to stay current. With a regular worktree I could just pull, but now I have to remember the branch, fetch all and reset hard to the remembered branch.