In that case you either were aware of the risk of your device breaking down in the future and have started looking into migrations or workarounds the moment the news hit, you took the risk that didn't happen and now have to deal with the consequences or you just didn't plan ahead enough.

Just keep running the older version of Windows that worked with the device. Add a couple of layers of configurations, firewalls, VPNs, traffic monitoring and whatnot inbetween to reduce the risk and don't connect the device to the internet. Your solar panel farm doesn't need to access Gmail or run Windows 10.

Your obscure SCADA device is your responsibility. The switchover to 32bit had been announced 20 years ago and the switchover to 64bit 10 years ago.

Also, if the manufacturer doesn't exist anymore, where are you going to source replacement parts?