When the POS module is active, Stripe is your payment gateway, and you've saved a Stripe account ID and secret key, editing an existing location shows a Stripe Readers card: a table listing ID / Label / Device Type / Status for each registered card reader, an Add New button to register a reader by its registration code, and a Disconnect button on each row.

The reader list, and the Add/Disconnect actions, only actually work for a location flagged as a Retail Location (created/managed under Settings > Delivery Settings > Retail Locations). Opening the same card on a plain Pickup Location or Wholesale Location returns an "Invalid retail point!" error, so the table stays empty and readers can't be added there even if the card is visible.