The persisted and regular groups exist independently and probably will not be a problem in the future.Yes I'm aware of this. But apart from wiim specific features generally all audio pro speakers (as far as I know and tried) can be grouped with wiim devices and controlled via the wiim app and vice versa. This is quite important for my use case, as it means my mix of wiim and audio pro devices can all be grouped together (via the app or automatically via home assistant), which was actually my main reason for going with the wiim amp after owning several audio pro speakers. And I hope this continues to work, even when new wiim features like persistent groups are released.
Hypothetically if such a feature would break compatibility with audio pro features like grouping, I would have to get rid of all my wiim stuff and get audio pro streamers instead.
As @Burnside already mentioned, AudioPro speakers (non WiiM edition) simply cannot be included in a persistent group.