The path to general computation on Bitcoin (with OP_CAT)

Heard this mentioned before, what exactly can you do with 4 bytes? Is this related to the M31 field? But how do these 4 byte elements relate to something like a distribution of funds? I keep getting stuck on that one would need to construct a CTV hash or a hash of a signature on stack somewhere along the line. (ofc this is trivial with CAT)

If I understand correctly, CAT is actually used for SPLIT, to cut an arithmetically useful sized chunk off of a cryptographic hash?

Yes, LNhance does not provide generic data carrying capability.