Integrate NextAuth in .NET environment

Question

I've developed an application utilizing Next.js for my client side, and an ASP.NET Core 8 Web API for my backend.

The auth flow is fairly simple. My backend issues short-lived access tokens, along with refresh tokens for seamless user experience. On the client application, I have a middleware that checks the requests and validates them for those protected routes where a logged in user with those privilege's has access to them, along with axios interceptor that refreshes the access tokens.

So, basically overall a custom auth implementation on both the ui and backend.

Recently, the client came up with a new change request that requires integrating OAuth2 with Google social login in the scope of the platform of what we already have, in order to enable the users to choose how they wish to register into the platform, by enabling those users that will register with google to have several extra functionalities with the Google services.

My question is, what approach should I take from this moment onwards? Migrating fully to use Next Auth seems like a fairly good solution to implement, but this will have a lot of reworks to be done on both the UI and backend side.