Is it possible to run Bitcoin on Google App Engine? / alternatives?
You should have a look at this (my master thesis topic connected to running Bitcoin on GAE).

While it is possible to run a Bitcoin-related application on Google App Engine, the service will inherently depend on another application to run. GAE only allows one to use the most basic ports for HTTP and HTTPS communication, whereas running an independent Bitcoin node requires the use of TCP/IP. It is possible to write a simple program to convert HTTP calls into TCP/IP ones, but that would need to be hosted elsewhere. If you want to use Bitcoind as the way to communicate with the Bitcoin network, things get significantly easier.

I've tried writing my own implementation of a Bitcoin client on Google App Engine in Go, but was ultimately defeated by OP_Checksig and its lack of documentation. But honestly, I found using Bitcoind for everything Bitcoin-related to be a lot simpler.

What you also need to consider are the costs of running apps on Google App Engine. I personally found the write and read operations to be a bit limiting if you want to stay on a free tier, but depending on what you will actually want to do, there can be other factors to consider.