Use BIP39 to generate SSH or TLS keys?
SSH is a generic protocol within which a user can deploy keys from a variety of algorithms, one of which is ECDSA (same as Bitcoin signatures).
The Ledger hardware wallet even has an application for its devices to perform SSH signatures using keys derived from the same seed used for cryptocurrencies.
TLS also has EC available as an algorithm so there might be a way to use your BIP39 seed for this as well.