I recently made the move away from an out-of-support macOS 12 Monterey to Debian Stable (13 trixie), after some failed attempts to upgrade macOS using OpenCore Legacy Patcher.
While Linux support will always remain far from perfect with that series of MBP, it was still much better than I expected compared to my last look many years ago. I happen to get better use out of my particular setup now compared to macOS; as it's basically a glorified streaming device that I interact with through wayvnc/vncviewer out of arm's reach across a table. This also allows me to mostly avoid using the semi-busted Butterfly keyboard.
In addition to having something with security updates again, I'll now never need to think about Apple dropping Intel support. I'd also like to note that nix-darwin support on Intel macOS is ending very soon too - but not Linux + nix as a package manager (nixpkgs) since that combination is separate to macOS + nix-darwin.
Fortunately, those can run Linux. I recently installed Arch on an Intel T2. The only issue is that it does not have a TPM module, so the LUKS password needs to be manually entered at boot.
You can use TPM with secure boot to store the password. TPM checks that the firmware is the same and that the OS is signed by trusted (by _you_) keys, and if everything matches it makes the key available for reading by the OS.