With Scotty, how can I combine ScottyM with a custom monad with ScottyT

Question

data MyAppR = MyAppR {
  dbPool :: Pool Connection
                     }

type NewApp = ReaderT (MyAppR) IO
type AppActionNew a = ActionT L.Text NewApp a
type AppServerNew a = ScottyT L.Text NewApp a

type App = IO
type AppServer a = ScottyT L.Text App a
type AppAction a = ActionT L.Text App a
type AppActionT = ActionT L.Text App

How can I define a function such as:

mylift :: AppServer () -> AppServerNew ()
mylift a = undefined

Posting it in case anyone already has a solution, otherwise I'll just be figuring this out. Unfortunately ScottyT / ActionT is not a monad transformer so I can't just do the usual lifting.

---

The whole reason for this is, I now need a database pool for my application, but I don't wanna bother with changing the AppServer type everywhere and then lifting in all the places. Probably it's quicker just to combine and mix AppServer with AppServerNew.

Initial solution that typechecks - but doesn't seem to work correctly as all 'handlers' respond with 404:

mylift :: AppServer () -> AppServerNew ()
mylift (ScottyT x) = pure $ evalState x def