Their how-to-use intro says,
The easiest way to use PocketBase is by interacting with its Web APIs directly from the client-side (e.g. mobile app or browser SPA).
It was designed with this exact use case in mind and it is also the reason why there are general purpose JSON APIs for listing, pagination, sorting, filtering, etc.
Other than the web API, there are also Javascript and Dart SDKs.
From Pascal, the API is your best bet. Then you're building a Pascal SDK for Pocketbase, essentially. But
https://github.com/pocketbase/pocketbase/issues/945 was closed "not planned" on providing an OpenAPI/Swagger API spec. So no automatic code gen, meaning you'll have to wrap the APIs in Pascal manually.
Pocketbase is a simpler, one-server non-scalable clone of Firebase/Supabase. The latter two have unofficial Delphi SDKs which may or may not be usable with FPC/Lazarus.