A manual update works. It's the same thing HPM does under the hood, and it's the way we all did things (and many still do) before HPM existed. If this process failed for someone else, it is because they did something wrong, not because there is something wrong with the process itself. (Maybe they mixed up the parent and child app code?) Such problems are avoidable by following instructions.
Hubitat does not normally commit to timelines for any releases, but I'd expect you'd need to wait until at least 2.3.9 for this since 2.3.8 is probably done at this point.
You don't have to re-create all your pistons, though depending on your setup, you may still need to address some issues afterwards. See: webCoRE built-in on Hubitat - Do I need to transition and how?
