Yeah that was my answer, chunk it down using bitwise commands and mod 255. This is essentially how it will work in future (e.g. someone will make an ArrayBuffer library that just uses [Nat8] and has functions for each of these). Currently doesn’t exist in Motoko (publicly) but it’s not too hard to create one.
I know there are some motoko libs out there that aren’t public yet from community devs and most likely dfinity devs too. It may be within mo:pirm haha - although I think dfinity don’t want people to rely on that going forward.
There are dev grants available, could be an idea for someone to apply for funding to build out additional types link ArrayBuffer etc (with corresponding functions like fromNat, fromText etc).
Currently Nat and Int are implemented using wrappers around LibTomMath (https://www.libtom.net/) but that’s an implementation detail that could change. There is no way to access the raw representation from Motoko (by design). That doesn’t mean we couldn’t provide some way to iterate over the raw bytes in future though, if desired.