Accounts and hashing in smart contracts

Can I hash any byte string inside a smart contract with SHA, send algos to it and make it a valid, “active” address?

Whatever happens, the new account will be created and funded (as long as you transfer at least 0.1 Algo).

If you hashed a byte string that is a valid description of a TEAL program or a multisig, then you would be able to sign transactions out of this account.
If not, the funds are essentially burnt.