Personally:

- Google Cloud Run (or anything that can run docker)

- SendGrid (but use SMTP only for easy migration)

- Google Workspace (Office/Notion are also cool but I just don't use them often)

- Mainly Go with Python for scripts

- PostgreSQL

- gRPC/Protocol Buffers for API servers

Where possible I try and take on as few dependencies on big cloud services, and always use standard gateways. It makes moving around much easier. Other stuff mentioned here is quite good, but I'll especially recommend https://IndieHackers.com