I think a basic native app could be good - a simple method to add clients, enter and send invoices and enter purchases. (Maybe further down the road stripe integration to allow customers to pay an invoice on the spot.)
Anything more complex like registering other payments, bank account transfers, drawings and uploading receipts etc. can all be done via the website. when back home.
Alternatively, is there an API (even if it’s under an NDA) that an app developer could use to write their own native app for QF to do some of these functions?)