I’ve made the effort to secure mine and am aware of how the trusted protection module works with keys, Fedora’s Anaconda system, the shim, etc. I’ve seen where some here have mentioned they do not care or enable secure boot. Out of open minded curiosity for questioning my biases, I would like to know if there is anything I’ve overlooked or never heard of. Are you hashing and reflashing with a CH341/Rπ/etc, or is there some other strategy like super serious network isolation?
No point in putting locks on your house, because an attacker can just drive their car through your front door.
The attacks you mention have their own ways of being detected: usually eyeballs. But eyeballs can’t help you against something hiding in your bootloader. So Secure Boot was made.
And I don’t really follow your dual boot claim. If you don’t trust one of the OSes, and you boot it up on your hw, you’re already hosed. At that point it can backdoor your bootloader and compromise your other OS. Secure Boot prevents malicious OSes from being booted, it can’t help you if you willingly boot a malicious OS.