I'd like to recommend the friendly people at Oregon State University Open Source Labs [0] who host POWER resources for open source projects. If you're looking to see what the ISA can do on P8 or P9 system, I'd definitely contact them and see if you can get a VM.

There's also a cool vector library [1] that bridges the gap between different versions of the ISA and different compiler versions.

[0]: https://osuosl.org/services/powerdev/ [1]: https://github.com/open-power-sdk/pveclib