I am intrigued by the Proton Unlimited plan but am only allowed 500GB of storage. One Drive gives me 1TB with a subscription to Office 365, but allows for the option to purchase additional storage tiers ($9.99/1TB)

iCloud+ is even better with being able to purchase plans in 2TB increments for $9.99/mo and lac out to 12TB

For users of the Unlimited and higher plans, make it easier for users to get more storage in increments if needed.