Well, that's quite an username. To be honest, fair and biased, it's either SvelteKit/Postgresql or Django with SvelteKit. We (basically me alone, just sounds cool using 'we') developed this forum using Django with SvelteKit. I would really suggest that.
And for Phoenix, it's really an awesome framework, you can also go with that. It's fast, but if you're fine with elixir, go with it.
To be concrete, Django (with Django Ninja or Djapy) and SvelteKit. Done.