Deploying this requires running 5 different open source servers (databases, proxies, etc), and 5 different services that form part of this suite. If I were self-hosting this in a company I now need to be an expert in lots of different systems and potentially how to scale them, back them up, etc. The trade-offs to be made here are very different to when architecting a typical SaaS backend, where this sort of architecture might be fine.
I've been going through this myself with a hobby project. I'm designing it for self-hosting, and it's a radically different way of working to what I'm used to (operating services just for my company). I've been using SQLite and local disk storage so that there's essentially just 2 components to operate and scale – application replicas, and shared disk storage (which is easy to backup too). I'd rather be using Postgres, I'd rather be using numerous other services, background queue processors, etc, but each of those components is something that my users would need to understand, and therefore something to be minimised far more strictly than if it were just me/one team.
Huly looks like a great product, but I'm not sure I'd want to self-host.