So I have gotten BIP32, and BIP39 working in .NET Standard 2.0 and have made them nuget packages. The goal of this was to make these compatible with Ed25519 Elliptical Curve which is what Stellar uses.
This will let you create mnemonic pass phrases and also have HD Wallet support using path derivation. I have combined these two together in a small example I put together called dotnetstandard-stellar-hd-wallet.
It's not a lot of code but it was challenging to get it all working. As always I made the code VERY easy to read and modular so porting this into other languages should be VERY easy!
BIP32: https://github.com/elucidsoft/dotnetstandard-bip32
BIP39: https://github.com/elucidsoft/dotnetstandard-bip39
HD Wallet Example: https://github.com/elucidsoft/dotnetstandard-stellar-hd-wallet
I will be adding documentation to all of these but for now I wanted to get them out there so other people can use them.