I agree that there is no single, best solution for everyone, as everyone has different needs and different ideals. And it does not make sense for you to spend lots of effort and complicate the product unless there is real benefit.
One extreme would be to charge for actual metered usage (CPU & storage).
At the other extreme is just one single plan with no flexibility - certainly that would disappoint many customers, but is simpler to understand and easier to implement.
That will work for many cases, if these free users are still subject to permissions that can restrict their views, and the notification system also works for them.
A user with access to only a single app is not ideal, because it really changes how I have to think about designing my Workspace. But it is a good direction. I would prefer a different structure, perhaps a user with write access to just one or two views.
The ideal for my own case would probably be metered usage some limited users, since I expect that mostly they will use very little. But I know that is problematic and hard to sell.