You can host static sites on DigitalOcean's app platform for free. Their lowest tier offering for non-static sites is like $5/mo. Might be worth checking out.
For what kind of an app? If I was tasked to put an app someplace today, the answer would depend if it was easily containerized, and what kind of scale you're talking about.
For small apps, if containerized, I would host on Google Cloud Platform using App Engine Flexible Environment: https://cloud.google.com/appengine/docs/flexible
Add on their managed database, of course.
But also, random VPSs are so cheap that if it works fine as is, you could do a lot worse than just running it on Linode, Digital Ocean, Hetzner, etc.
So I take this opportunity to ask, what alternatives have people moved to? I really haven't gone back to look what's out there.
Not looking for free, just alternatives to review.