"Relay Premium is available in the United States, Germany, United Kingdom, Canada, Singapore, Malaysia, New Zealand, France, Belgium, Austria, Spain, Italy, Switzerland, Netherlands, and Ireland. "
(https://relay.firefox.com/faq)
Now you can, up to 4TB: “ With Apple One, you can choose a subscription plan that includes 50GB, 200GB, or 2TB of iCloud storage. If you need more iCloud storage, you can buy more for a total of up to 4TB. ”
"Relay Premium is available in the United States, Germany, United Kingdom, Canada, Singapore, Malaysia, New Zealand, France, Belgium, Austria, Spain, Italy, Switzerland, Netherlands, and Ireland. " (https://relay.firefox.com/faq)