I am currently using https://github.com/romanz/electrs for various stuff, but unfortunately I dont find any api details anymore.
The documentation for the Electrum Server Protocol is the same as for ElectrumX, i.e. this one: https://electrumx-spesmilo.readthedocs.io/en/latest/protocol.html
Electrs most probably also follows that.
As you can see here, generating addresses from an extended public key is not that hard.
That being said, existing solutions can be found easily on GitHub. This one for example, seems to fit almost exactly your description; since it's in JavaScript it should be easy to embed it in a NodeJS application with API that you add yourself. https://github.com/swan-bitcoin/xpub-tool
Thanks, I will look into that and update, once it is working.That being said, existing solutions can be found easily on GitHub. This one for example, seems to fit almost exactly your description; since it's in JavaScript it should be easy to embed it in a NodeJS application with API that you add yourself. https://github.com/swan-bitcoin/xpub-tool