My Pixel 4a is getting its software support dropped, meaning no more security patches and increasing vulnerabilities. So I installed LineageOS for microG, a fork of LineageOS that has microG. I chose this one because LineageOS has good support for "older" devices like mine unlike GrapheneOS, and getting microG bundled in the fork is a turnkey solution for getting me access to Google services when I need them.
The installation process itself was very simple, I just followed the guide on the LineageOS site and ignored the optional stage for installing a GApps package since I already had microG. The pre-install work was more complicated, and required downloading a few tools and drivers for the Android Debug Bridge (adb) to work. I think this is the biggest barrier to entry - if you can get everything set up for the install, you shouldn't have any trouble with it.
After loading in and getting basics like Wifi and fingerprint lock set up, I was off to the races. The install comes with a very lean set of FOSS apps, as well as F-Droid to grab more. I immediately went and got Aurora Store off there so I could access the Play store and all its apps, which worked without a hitch. In fact, everything I've installed has worked as well as I would expect with the stock ROM with the exception of Google Contacts, which would not sync from my google account (and I can't even definitively say this was a ROM-related issue). Even my banking apps work despite my device not passing the SafetyNet check. Your mileage may vary depending on your apps and their requirements, but I myself was pleasantly surprised. The only thing I think I'm losing out on is NFC payments using Google Pay, but that's not a big deal for me.
Barring that one exception, everything just works and I'm glad I went this route. I was already happy with my Pixel 4a, and buying a whole new phone just because Google decided it couldn't be bothered to update it anymore would've left a bad taste in my mouth, especially as I'd be giving up features (headphone jack and fingerprint sensor on the back) I value. Now it's time to ride this baby out for as many more years as I can.
Just as a general rule I'd advise against ever using biometrics to lock anything, especially your phone. Cops can legally force you to unlock your phone with biometrics but not with passwords.
is this good advice? yes
will i follow it? uhh