Update boot partition on a Pi - necessary? How?

Hi all,

my first release upgrade on the Pi platform - 14.0 --> 14.1.
Smooth as usual. Special thanks to ronald@ for the
smsc(4) improvements.

Now I wonder how to do what I regularly do on amd64,
namely update either the legacy boot partition or the
EFI boot loader?

What *are* all these files on that FAT partition, anyway?
Is there any documentation on this?

Thanks for pointers.

Kind regards,
Patrick