depends what you use but most PaSS that has built in deployments, usually have the monorepo option of using a specific directory. I use vercel for my next app and railway for my backend and I basically have a monorepo, in my github action I simply call vercels or railways up process in the directory, nothing else to it.
Using Monorepos | Vercel Docs (this won’t be multiple PaSS)
And yeah the docs of the services you use usually have this information.