The kind of fascinating thing about doing notes this way is that it’s theoretically a web page so you can kind of do anything, but I’m curious to see what is actually supported in apps
Fastmail’s editor on the web just has basic formatting, size, colors, links, lists, alignment
iOS notes will let you do a lot of wild stuff but I don’t know how much of it is specific to iCloud because they don’t give you anything but plain text if the account is not iCloud. Which I guess is safe, but also lame