I've currently got a web app I'm just self-hosting on a DO VPS for $5/month. I have a Postgres DB on the same VPS (via a Docker image), with a 10-line shell script & cron job for backups to Backblaze B2 (which costs ~nothing/month for my tiny DB).
Additionally, my web app is a Kotlin API and a Nuxt.js SSR server, so I think I'd have to set it up as two separate "apps" on this platform. That means I'd be going from $5/mo to $25/mo.
On one hand, that's not a ton in the grand scheme of things. On the other hand, the whole reason I use DigitalOcean and self manage my infrastructure is to _not_ have to pay that kind of money for my projects with no revenue.