I am glad someone is tackling this problem.
A feature request (or perhaps an architectural direction) would be if you could accommodate the backend behind graphql instead of Django+MySql, there's a potential for it go full Serverless (frontend and backend) with JAM-stack frameworks like redwood.js [1] (backed by apollo-graphql) or using Cloudflare Workers [2].
Edit: Another question I have is, is posthog at 80% feature parity with mixpanel / amplitude / heap already? If not, what do the timelines look like (asking since you're OSS, though, it is understandable if you can't reveal just yet). May be there needs to be a page on competitor-matrix on the website?
[0] https://github.com/PostHog/posthog/commits/master?after=9ae6...
[2] https://blog.cloudflare.com/jamstack-at-the-edge-how-we-buil...