My day has finally wrapped up after spending far too much time trying alternative operating systems for my phone. The goal was to completely remove everything Google and replace them with (at minimum) adequate replacements. The goal was mostly successful, as I'm only left with Google Fi. That one is unavoidable, as they are my mobile carrier.
Long story short, LineageOS is the best of the alternative systems. It's regularly updated, has a lot of features, and is now living on my older OnePlus 5T. My current phone, the OnePlus 7 Pro, is a massive pain to work with and has caused me nothing but panic and headaches.
I'll skip the "how" and simply say that my phone is running stock with lots of stuff removed. This solution not only has the best battery life and manufacturer support of the functions required for the base hardware, but it's also a fairly clean and minimal OS to begin with. Clearly it comes with some bloat, but that was taken care of when removing all the Google integrations. I would have stuck with LineageOS, but aGPS wouldn't get a timely position fix, and I couldn't get root to work consistently enough for editing the files required.
My phone is much cleaner now, and I feel better not having the big four (GOOG, FB, AAPL, TWTR) anywhere nearby.