(Render founder) Any chance we could connect about the issues you saw with Render? Email in profile. Lots of former Heroku customers spending thousands of dollars every month have successfully made the switch to Render and are quite happy (as you can see elsewhere on HN). I'd appreciate a chance to address your pain points with us.
Probably not, but generation focus is pretty good at connecting companies with specific subsets of users. I know they already maintain a list of current heroku devs.