Oreole is not a plug-and-play yet. From their docs ( https://www.orioledb.com/docs ) > OrioleDB currently requires a set of patches to PostgreSQL to enhance the pluggable storage API and other PostgreSQL subsystems. All of these patches have been submitted to the PostgreSQL community and are under review.
(Opinions are my own, not of my employer)
I think that "under review" claim is doing some very heavy lifting, especially when it relates to their changes to index tuple lifecycle management. The patches that have been submitted are unlikely to get committed in full anytime soon, even after substantial changes to the patches' designs.
PostgreSQL just has not been designed for what OrioleDB is doing, and forcing OrioleDB's designs into PostgreSQL upstream would a lot of (very) sharp edges that the community can't properly test without at least a baseline implementation - which critically hasn't been submitted to upstream. Examples of these sharp edges are varsized TIDs, MVCC-owning indexes, and table AM signalled index inserts.
There are certainly ideas in OrioleDB's designs that PostgreSQL can benefit from (retail index tuple deletion! self-clustering tables!), but these will need careful consideration in how this can be brought into the project without duplicating implementations at nearly every level. A wholesale graft of a downstream fork and then hoping it'll work out well enough is just not how the PostgreSQL project works.
Oh this dampens my expectations, I was under the wrong impression that it will stabilise outside of Postgres before it is merged.