I tried to find out what key algorithm is used -- not listed anywhere. Everything led to pages about Blech32 (a bitcoin key encoding).

https://hellonostr.dev/en/introduction/

The encoding seems to have an unmentioned/unaddressed version number included, both in the nostr doc and the bitcoin docs.

npub1abcxyz... is npub (header) 1 (version) abcxyz... (key)

Now take a look at the doc (linked above.)

nip01 defines the use of secp256k1. Again, the same as bitcoin.