And to add insult to injury, you as the user do not get to have a root account. Yes, there are ways to get one, but even the "alternative distributions" go out of their way to make it extra tedious for you. I would for example expect a built-in menu in Lineageos settings called "enable root" that does what it says without further steps.
Instead I need do install some 3rd party stuff from somewhere, get the bootloader image from somewhere, patch it, use a PC to install that image... for each update!
In theory, sure. However, having done that dance before, the limitations between a degoogled Android (basically open source apps only, since F-Droid doesn't allow proprietary apps, and nearly all proprietary apps depend on Play Services APIs anyways), you end up with something less useful than a PinePhone.
And at the end of the day, Android was written by Google for Google to serve Google. Trying to use a phone as your daily driver running developed by your enemy is hardly a way to get through life. Just get a phone that doesn't hate you. Like a PinePhone. Or an iPhone, which has all sort of issues but at least gives you a reasonably private and secure device at the expense of gobs of money.
MicroG may still ping google services sometimes, but it is not a root level backdoor into my phone. Most proprietary apps I've tried work. Bank app, dating apps, slack, visual voicemail, venmo.
Early development or not, the rk3399 is a 5 year old SoC.