I run a small business and I would like to accept credit / debit card payments on my Android phone running #GrapheneOS

Does anyone know of an app or paired terminal which will work?

SumUp asked me to turn off Developer Tools, but still said the device didn't meet the security requirements for accepting payments.
They offer a Bluetooth paired card reader - but I don't want to spend £30 if it won't work with Graphene.
Anyone have experience *receiving* tap-to-pay on their GrapheneOS device?