The osdev wiki is the best source for this and they have the bare bones tutorials with all the linker scripts, bootstrap code, makefiles, etc you might need. They have examples for multiboot and UEFI (and BIOS boot sector).

For Rust there's this popular series: https://os.phil-opp.com/

If I were to start a new OS project I would do it in Rust too but as awesome as Rust is, I can't recommend doing a bare metal project as your first foray into the language. Learning two or more things at once doesn't work for me.