Using vars in jsonbpath operator ?

I understand that on a where clause a gin index can be used for the following predicate

a.data @? '$.results.docs[*].accs[*] ? (@.id == “123")

I have a join query however on the following condition

jsonb_path_exists(a.data, '$.results.docs[*].accs[*] ? (@.number == $id)', jsonb_build_object(‘id', b.id)) but this cannot use a gin index afaik and results in a seq scan.

Is there anyway to use the operator syntax above by passing the b.id <http://b.id/> variable somwehow so that the gin index can be used ? ?