Assuming that’s true, they can demand all they want, but you can’t just:

if government_order == true: iCloud.unlock()

…assuming they use any of the usual encryption algorithms.

Proton services are encrypted, but if Andy Yen goes full nazi (which he haven’t done yet), he could just send you a javascript on the browser UI / update the apps, with code that extracts your keys and sent it over to their servers.

And they could force the update by refusing you to access your data until you’ve updated.