This is the idea. The standard will be to accept payments in Bitcoin for every block merchant, they will receive in USD, and they will not pay any fees in 2026. But you need to ask for a qr code to pay specific in BTC Here's a website to search every square merchant

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I heard it was an "opt-out" service, which should mean that it is Bitcoin enabled by default? Also, is this US only or is Canada included?

I just don't know? I assume it's enabled everywhere as a form of payment. Can a business turn it off?