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.
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.
Thomas Arbor Bandcamp (includes I.Ryoko releases)