It's why I'm on digital ocean. Cheap, but good quality service that's comparable to the big boys and it's capped. $5/month is perfect for me

I use Heroku for these situations where everything is managed automatically. The only con here would be paying more, $20-50/m (Node.js+DB+Redis?) instead of $5/m for DO, but I'm happy to pay for that and spend no time on manual management.

You can definitely set limits on GCP

The trouble with this is what do you do when your "max spend" is reached? Shut everything down? Shut parts of it down? Most "real world" systems aren't built to have the stool kicked from underneath them like that, so there will be data/business loss and pissed off customers (and in the case of Cloud also pissed off customers' customers).