I want this on my own homeserver. Protection against someone stealing the server without requiring me to type a password every boot.

In what way is TPM protecting your data if someone steals the entire server? TPM only ensures that the boot environment has not been modified. Whatever key is being used to automatically decrypt the disk would be in the clear.

Unless I'm misunderstanding your situation, I think you should look up the "Evil Maid Attack" to better understand how to mitigate risk for your threat model.

assuming there are no bugs in linux and you enable full memory encryption in BIOS, it protects you in the same way the FBI cant get into a locked iphone they physically posess

but linux is not as secure as an iphone, and linux users typically dont know how to set this up, so in practice you are right, it doesnt protect you

My threat model is a junkie breaks in to my house and flips my server on facebook marketplace. Then the buyer curiously pokes through my hard drives. Of course if protecting against government agencies is the threat model then TPM alone isn't enough.

For me, a zero friction way to have decent security is worlds better than the normal state where homeservers are not encrypted at all.