I’m unclear how mature the project is and whether it will be updated in a timely manner long term
ublue and bluefin co-maintainer here, we've been around for a while now (3rd birthday coming up!) and have been around in a more unofficial capacity for longer.
Bluefin is feature complete and is in maintenance mode, it's just going to get updated in perpetuity to 41, 42, etc. We invested in automation first so most of the maintenance is automatic and it doesn't take much for our team to do it. Right now most of our major ticket items are waiting for things to finish landing in upstream Fedora, most of which are targetted towards F41. A good portion of the team have been around in OSS for a long time and a bunch of us work in the industry and depend on Bluefin for our jobs, so much so that we have a great working relationship with Framework, so we're supporting those laptops as a community option for them.
Aurora is relatively new, coming in just as Plasma 6 landed in fedora. Most reports with issues we get for it are things like it being a new major release, wayland/nvidia issues, etc.
Hopefully that answers some of your questions, if you have more feel free to ask!