That pricing model seems rather inherently tricky to me, and also quite expensive. At $1.50 per 10 million rows read this can get very expensive the moment you do a full table scan on any non-trivial table. And while this example is a trivial case where you only need minimal database knowledge to ensure that no full table scan is necessary, many real world cases are much more complex.
It also seems very expensive compared to just renting DBs by instance, if you put any real load onto this. I can see this being attractive if your use case only queries single rows by key, but it's essentially a big minefield for any query more complex than that. A database with a rather opaque query planner doesn't seem like a good fit for this kind of pricing.
I agree with this. You are also only one bug in the query planner away from going bankrupt. Imagine Planetscale upgrading to a version which contains a small edge-case bug and now you owe them tens of thousands because of it.
It also seems very expensive compared to just renting DBs by instance, if you put any real load onto this. I can see this being attractive if your use case only queries single rows by key, but it's essentially a big minefield for any query more complex than that. A database with a rather opaque query planner doesn't seem like a good fit for this kind of pricing.