I had read about them before but for whatever reason it never clicked.
Turns out I already work like this, but I use commits as "PRs in the stack" and I constantly try to keep them up to date and ordered by rebasing, which is a pain.
Given my new insight with the way you displayed it, I had a chat with chatGPT and feel good about giving it a try:
1. 2-3 branches based on a main feature branch
2. can rebase base branch with same frequency, just don't overdo it, conflicts should be base-isolated.
3. You're doing it wrong if conflicts cascade deeply and often
4. Yes merge order matters, but tools can help and generally the isolation is the important piece