Indeed, this has been a problem for years.
I used to stop kingdom progression @ Power Level 20, as there is nothing the game could offer to help me pass the old “Challenges” task.
However, they released an update in May 2023 that changed Challenges to Trials. You can see me complain about it here.
I had to refresh my memory on this, as I’m getting older. Part of the Trails update was the introduction of Epic Trials, and with it the Starry pets. I’ve already moved so far beyond this system I forgot it existed entirely. LOL
Anyways, I wanted to make sure I had all the Starry pets just in case future Power Level tasks required them. They haven’t expanded the PL’s yet so remains to be seen.
Since I was knocked off my perch by this new system, I’ve taken to parking most of my kingdoms on the “Level x pets to 20” (PL’s 22 and 26).
This causes the Kingdom offer to typically be a pet – not necessarily one that I need (checking for that would be too difficult…) but it’s at least more helpful than ingots.