The platform itself is not even source available. I think it's a bit disingenuous in that case. At Windmill (https://github.com/windmill-labs/windmill), we are actually building the OSS platform that you can self-host and that is an actual OSS alternative to ... pipedream.
If you mean the paid registry thing that they sell, which allows you to keep track of your installations of Netdata on multiple servers, then no.
There is nothing paid, everything is free, both the agent and the cloud app. Do whatever you like with it. There is a pricing policy that will follow sometime in the future but everything that is free today seems that will remain free forever.
It is ok to pay in the future for SSO.
My concern is not money at that moment, but the foot print on production system as data will be stored and queried next to prod with recently introduced anomaly advisor on top.
There are plans in the future for some paid plan but it won't remove features, it is more on having longer retention on metadata, role based access, support, etc.
You can find more details here https://www.netdata.cloud/pricing/