Agreed. Network control and secret injection together with a microVM setup is as good as it gets right now, although I believe that we need more fine-grained tools down the road. It sounds like Microsandbox would be the perfect fit for what you are describing. I also built my own coding agent workbench on top of it (https://github.com/isolade/isolade). Microsandbox is quite cool, check it out: https://github.com/superradcompany/microsandbox

I would totally prefer to buy something without spyware. But so far I have not found a good alternative to my 42" C-series OLED. You do have to carefully configure it to not phone home, but besides that (and some minor problems with peak brightness), it's great. If there was a non-spyware replacement, I'd buy it.