Contemporary compositions for theatre are the main thing Arbor (previously I.Ryoko) is up to, with two collections of theatre soundtrack work available via his Bandcamp.
Winner of the prosaic title award, Theatre (2021), collects 11 beatless tracks from several different theatre productions.
RIB (2021) is also the soundtrack to a production, in this case a 2017 “dance-theatre piece” of the same name. It has one or two beat-y tracks, but mostly fits the ambient envelope to some degree.
Arbor’s Bandcamp page also includes releases from his previous alias, I.Ryoko, which are often plenty ambient as well.
Links
Thomas Arbor Bandcamp (includes I.Ryoko releases)