It is now possible to enable hostspot/tier1 in Github Actions at least for 64-bit builds as problematic compiler/rtm tests have been problem listed [1]. So far only for 64-bit builds, as there are still some tests failing for 32-bit builds, which need to be fixed, before it (hotspot/tier1) can be enabled there.

All tests passed.

[1] https://bugs.openjdk.org/browse/JDK-8295915