Poking at things a bit more. It turns out my Ventoy drive hadn't died after all, just wasn't happy with my other PC for some reason (but that's a problem for future me). So I can boot up the old ISO and check things out. Previously, when I booted the 4.3 ISO the Bluetooth worked but WiFi (and built-in Intel LAN) did not. After install + upgrade, WiFi works and Bluetooth does not. Admittedly, WiFi is more important to me right now than Bluetooth, so I consider that an improvement in the situation.
If I need to boot that up and gather more logs I can do so. I may also try booting another distro (probably endeavorOS) and see if things work over there. (No chance of me distrohopping though - I vastly prefer working with Solus infrastructure.)
Oh, and another note - if I switch Bluetooth on and then off in the Budgie Control Center GUI, I do get an applet icon that indicates Bluetooth is off. But when booting, or when switching on, the applet icon doesn't appear in the system tray.
As I see it, the current most likely culprit is firmware. It's probably worth trying to bisect changes to the firmware files and see if I can find one that does both WiFi and Bluetooth for me. I recall seeing a thread somewhere that pointed out the specific file, so I guess I'll have to go dig that up again 😁
Thanks again to all for help. I think my next steps are:
- Disable blueman-manager as @Axios has suggested and see if I get an applet (not sure if this is necessary considering what I posted above, but it probably can't hurt)
- Bisect changes to the firmware file and see if I can find a firmware binary that works for me
