Note: There could be light at the end of the tunnel.
/e/OS comes with FakeStore (now called App Lounge Store - not the same as the App Lounge used to install apps). It has the package name of com.android.vending, same as Play Store.
It is just a stub used by some apps that check for the existence of Play Store.
What is happening with some apps, like Weather Network, is that they are looking for a licensing function from the Play Store. It finds FakeStore, tries to get the info it needs but cannot. Hence the failure.
Even though the app is free I guess it’s coded to look for said function, even though not needed.
There was a pull request from five years back.
The fix finally happened.
Swapped out the FakeStore on one of my ROMs and retested. Weather Network runs without the error.
Another app that produced the same error also runs fine.
Hopefully we’ll get the new FakeStore in a future /e/ build.
I would consider it a priority actually.