Wrong again. It depends on the CPU. They can absolutely read a single byte and they will do if you're reading from non-idempotent memory.

If you're reading from idempotent memory they won't read a byte or a word. They'll likely read a whole cache line (usually 64 bytes).

And if you read the ARM article you linked, it literally says so.

Where?

Thus any compiler worth their salt will align all byte variables to words for faster memory access.

No they won't because it isn't faster. The CPU will read the whole cache line that contains the byte.

RTFM

Well, I would but no manual says that because it's wrong!