Postgres people need a solution just as much as MySQL people do. I think when it comes to Postgres, the name in my mind is Neon, even though I am a Planetscale customer. In my current job, I need MySQL, but to be clear I wouldn't be against Neon (even as a PS fan) if I had a direct need for it.
Neon has a reason to exist even if Planetscale is in the "lead." There is a huge community around Vitess, including, you know, YouTube, not to mention MySQL, which also has an enormous community.
Keep up the good work. Databases as a service are a good thing to be doing.