Currently, we integrated one of our customer with OpenID Connect, it’s working well, but the next step, they want our app could directly send request to their API as they already log in. So is it possible to store the access token of users to usermeta when they log in?
Perhaps you could elaborate on how you are authenticating users? Are you doing this via a SPA, web app, mobile, etc.? We do also have this page which outlines architectural scenarios as they relate to accessing an API from the aforementioned technologies/platforms.