I agree the site could do with more documentation, I have to read a lot of the site and I have tech background to really understand what is going on. It'd be nice to see a simple view of what you are getting (200G storage, email, matrix, In an encrypted VM, etc, etc) on the front page. Here is what I understand:

This product looks to be a hosted virtual machine that federated computer encrypts with your credentials. Since they encrypt the VM with your credentials they can't actually see your data in the virtual machine. The virtual machine has the ability to host a bunch of open-source software, and a control panel that helps you setup/manage all the OSS.

This offering reminds me of https://librem.one/ , although librem.one is just offering similar OSS and they host it for you in a shared env.

Their control plane not being open-source is a bummer, but this is common for software (look at ledger's software). As mentioned by @federatedcomputer, they plan to open source the control plane, and if using a closed source tool is a no-go for you, then you'll have to wait to see if they do actually release the source-code.

My concern with it is if it is an encrypted VM running on a hypervisor somewhere:

All in all I think this is a very cool product, I think the price is good too. I'm excited to see where this project goes, good luck!