That's quite hard because it is lack of motivation for people to build such mini-services with risk of being sued. It is quite easy to get some illegal stuff when you host a service without review which is almost impossible for individual service provider to do.

There is one way which may reduce the risk. Build your whole system in RAM including OS. When totally power off, everything is volatilized. To lower the cost of RAM, one could just put the OS and service in RAM, but let the encrypted data in drive with key in RAM/RAM-disk.

The difficulty here is building a OS in RAM. There are some tricks but most of them need a host which may contribute to vulnerability.