Do you want to develop a new coin (that is,  start a blockchain) or
are you interested in developing wallet software? The two are not identical and
can be implemented separately using different languages.

If a wallet (a private key management system) is your chief interest,
I recommend reading Nicolas Dorier's "C# Blockchain Programming" - google it.

Most of the standard blockchain software is done with C++, but you might
want to take a look at "alternative clients" subforum here.  There are
full nodes written with Go, JS, Rust, whatever, and starting a new blockchain
would mean forking one of them and altering the relevant parameters.