Heroku's free tier is good. GCP App Engine is pretty similar, a little more powerful, but also more limiting in how you build your app.
My pick for MVPs is AWS Lambda. It's very easy to get up and running, and you get access to the rich AWS ecosystem. Yeah yeah, the "unlimited scale" benefit will be great when you're accelerating user growth, but that's not why its a good pick for MVPs. Need a cron? Not too bad on App Engine, but pretty hard on Heroku. Cinch on Lambda. Aggregated logs? Easy on most managed platforms. How about distributed tracing? Ridiculously easy on lambda. Need a quick queue? Horrible on heroku, alright on google cloud, but on AWS? Create one on SQS, wire it up to a lambda, done. There's a learning curve, but the power of the AWS platform is really what makes lambda a great choice.
My pick for MVPs is AWS Lambda. It's very easy to get up and running, and you get access to the rich AWS ecosystem. Yeah yeah, the "unlimited scale" benefit will be great when you're accelerating user growth, but that's not why its a good pick for MVPs. Need a cron? Not too bad on App Engine, but pretty hard on Heroku. Cinch on Lambda. Aggregated logs? Easy on most managed platforms. How about distributed tracing? Ridiculously easy on lambda. Need a quick queue? Horrible on heroku, alright on google cloud, but on AWS? Create one on SQS, wire it up to a lambda, done. There's a learning curve, but the power of the AWS platform is really what makes lambda a great choice.