Throwing Scalingo [1] in here because I feel they get way less exposure than they deserve. We [2] offer a SaaS for medical device companies. GDPR compliance made us look for a EU-based company, and the recent Heroku situations (disappearing free tier and GitHub OAuth fiasco) made us switch to Scalingo. Scalingo is based in France.
Their PaaS is rock-solid. The UI sometimes looks less polished but that shouldn't detract from the fact that their service quality is really, really good. No problems so far. When I had questions, I've been in touch with their support - you have real engineers responding to your message in a few hours. Really cool.
I've recently come to increasingly appreciate profitable, bootstrapped startups, because they have (much) less incentive of getting acquired, subsequently shifting their focus to "scale" and "enterprise sales" (wait, which company comes to mind here.. ah, Heroku). Scalingo is bootstrapped and profitable.
Why not render.com or fly.io? Both are based in the US, so GDPR compliance becomes more tricky. They're VC-funded, so I have no clue what will happen to them in the future. Maybe they'll be profitable and their investors will say "oh okay, it's fine to have a boring, profitable startup in our portfolio". Maybe not. Likely not.
[1] https://scalingo.com
[2] https://openregulatory.com