Howdy Chris Bongers,
Great to have you here 🤩
I thought about scalability from the first days of daily.dev but the architecture was different than now. My rule of thumb is to use managed solutions that don't require massive DevOps efforts or even to use third party services as a whole. For example, we use Superfeedr for subscribing to RSS feeds.
I used Google Functions and App Engine (similar to Heroku) at the start. Now, most of the load is handled by Kubernetes which is more oriented to multiple services environment. Again I'm using managed Kubernetes, not my own 😉
Most of the architecture is documented in our GitHub (some of it is a bit outdated)
github.com/dailydotdev/daily
Regarding the mobile app, it's not coming anytime soon but we do work on a PWA with mobile support. We're a team of 3 people and I'm the only developer. We're trying to move fast but we have so many things going on. Stay tuned for news 🗞