Hello,
I am currently evaluating APIs to use with our setup and yours really comes close.
However, I am using a few recursive functions in postgreSQL, a function looks like this:

CREATE FUNCTION recursive_geo(integer[]) RETURNS TABLE(id integer, parent_id integer)
    LANGUAGE sql
    AS $_$
WITH RECURSIVE included_geo(iid, iparent) AS (
    SELECT id, parent FROM geo WHERE id = ANY($1)
  UNION ALL
    SELECT p.id, p.parent
    FROM included_geo pr, geo p
    WHERE p.parent = pr.iid
  )
SELECT iid, iparent
FROM included_geo;
$_$;

Which I then call like this:
select id as hasid from recursive_geo(${data.all.geo})
where data.all.geo is the parameter passed to the query
is it possible to do this with RestSQL?
Could I f.e. just declare "recursive_geo" as a table? (It is actually a temporary table after all)

Thanks a lot in advance for any help!