You misidentified your objection. It isn't sideloading removal, which isn't happening. It's developer verification, which affects the sideloading that remains available.
Just because you don't understand the value of verifying signatures doesn't mean it lacks value.
I recall the same alarm over secureboot: there, too, we can (load our certificates into secureboot and) sign everything ourselves. This locks down the system from boot-time attacks.
I will never ever ever be able to get friends and family access to third-party applications after this change.
Then sign it: problem solved.
Developer verification should also give them a hard enough time to install trash that fucks their system and steals their information when that trash is unsigned or signed & suspended.
Even so, it's mentioned only in regard to devices certified for and that ship with Play Protect, which I'm pretty sure can be disabled.
Google promised they would allow on-device sideloading
Promise kept.
their word means fuck-all and you know that
No, I don't. Developers are always going to need some way to load their unfinished work.