Yes, the Fuse can be used with anyone.
Before you pay with your Fuse card, you'll be prompted to select who you want to split the payment with. You can choose to pay with an existing group (e.g roommates) or select a friend from your contacts.
If you choose to select a friend from your contacts, they'll get a message from Fuse with instructions on how to join the payment.
Note: They'll be able to accept your invite & join the payment without downloading the app. Very useful if you're having dinner and want to quickly split the expense.