They were not the only ones, see PTC, Aicas, IBM, and a few others.
The big difference until GraalVM and OpenJ9 became available as open source, was that all those vendors made AOT compilation a commercial feature, and thus most devs never cared they existed.
In fact GraalVM was one of the main reasons Excelsior JET eventually closed doors.
Comments
They were not the only ones, see PTC, Aicas, IBM, and a few others.
The big difference until GraalVM and OpenJ9 became available as open source, was that all those vendors made AOT compilation a commercial feature, and thus most devs never cared they existed.
In fact GraalVM was one of the main reasons Excelsior JET eventually closed doors.