It would be easier, if there would be one standard combo that would be enough (e.g. something similar to the WireGuard). Currently there are many IoT devices that mention TLS-support, but they don't specify e.g. supported ciphers and hash functions.
In the case of TLS, at least, there is a set of mandatory to implement algorithms, so in principle two conformant implementations should be able to interoperate using those. Currently, they are:
- ECDSA with P-256 for signature
- ECDH with P-256 for key establishment
- AES_128_GCM for data encryption with SHA-256 for hashing and KDF
