> Do you know of any other uses for bytes that are not 8 bits?

For "bytes" as the term-of-art itself? Probably not. For "codes" or "words"? 5 bits are the standard in Baudot transmission (in teletype though). 6- and 7-bit words were the standards of the day for very old computers (ASCII is in itself a 7-bit code), especially on DEC-produced ones (https://rabbit.eng.miami.edu/info/decchars.html).