I am using OAuth2 in a separate context to connect with a 3rd party app/API, and I think that functionality would definitely be welcome as well!
For this feature request, I don’t think OAuth2 is necessary though. A Custom App already has access to who is running/accessing the Custom App through the Session (
session.currentUser). From the current user, you can access a few properties (name, email, etc.), but not the user’s Airtable API key. That’s what I think would be really helpful to add.
For Airtable-Airtable contexts, I don’t think it’s necessary to explicitly ask the user for their API key. If they try to make a call to another Airtable base (something the Custom App API doesn’t natively support) their key doesn’t have permissions for, the API would return an error and the app could display that.