It has very minimal code and its implemented in a robust manner. Unlike UEFI and the desktop implementation of secure boot, it does work well and it has not yet been exploited on pixels. Its way better to have any kind of OS integrity check than none.

In that case, have fun coding up your own bootloader and flashing it onto the device. If you can't trust the bootloader, then you can't trust anything at all from the operating system that sits on top of it, because it could be compromised. If you can't trust a bootloader, then the only thing you can trust is a pen and a piece of paper.

I'd be more worried about the ROM that runs before the bootloader that you can't inspect, or possible hardware implants if you don't trust the bootloader shipped to you from the vendor.

Ok what is your alternative? Android Verified Boot with a secure hardware keystore like the Google Titan M2 is basically the best thing you can get.

They are expensive

Sometimes you get what you pay for, and...

I don't want to give money to Google

I get that, but your purchase (the entire Pixel department, to be honest) is a drop in the ocean to their profits. They won't notice you not buying one at all. You're handicapping yourself in the mobile security arena (not being able to install GrapheneOS) to take the high ground and not effect a tech giant.

That aside, if you really don't want to give Google, buy one from a reseller and not from the Google Store.

I highly encourage everyone to buy their pixel phones for grapheneos secondhand. there's enough pixel fanbois out there you should be able to deprive any corporation of the money of your sale by buying a like new condition last generation pixel (Like an 8 now that the 8a and 9 are out)

If you don't want to give money to Google, why not take money from Google?

https://adnauseam.io/

Then, once you've offset enough money, then you can buy a Pixel at an overall loss on Google's side.

They are way cheaper than fairphones where I live.

Well, whether anything is problematic or not is highly subjective.

Do you consider no headphone jack to be problematic? Or that some think it was done intentionally to push their wireless headphones?

What about the use of slave labor? After realizing it was impossible to get away from that, they tweaked their slogan from a fair phone to a "fairer" phone.

How about the high price and little demand?

See what I mean? One person's problem is not everyone's.