I ended up not going down this route, not only because of the deployment issues but because of the cost of running all this:
- DigitalOcean App Component (Basic instance with 2GB RAM, Strapi recommended minimum) $20/mo
- Managed DB - starting at $15/mo
- Spaces - $5/mo
This is $40/mo.
The cheapest droplet with 2GB / 50GB Disk space (the faster one, Premium Intel) is $14/mo.
After solving some minor hiccups in the docker deployment, I could start Strapi with docker-compose.