With this launch, the 600,000 active developers within the Firestore community can now use existing MongoDB application code, drivers, and tools, as well as the open-source ecosystem of MongoDB integrations with Firestore's distinguished serverless service. Firestore provides benefits such as multi-region replication with strong consistency, virtually unlimited scalability, industry-leading high availability with an up to 99.999% SLA, single-digit milliseconds read performance, integrated Google Cloud governance, and a cost-effective pay-as-you-go pricing model.
Shouldn't have to replace it for a long time (if ever) and seems to work fine. More expensive than lead acid but more convenient than service appointment for a 12v battery.
I did the startup thing. The ROI was crap compared to working at Google.
If you want to do the startup thing go ahead. You will have more stress and less money at the end of it compared to Google but Google will still be there to hire you at the end.