I couldn't get it working when trying Numo with a friend
Is cashu.me supposed to be able to tap-to-pay?
(I guess I just need to configure something related to NFC on one or both phones?)
My friend's Android has cashu.me, installed via Chrome as a PWA.
I installed Numo on my phone; a Huawei P30 Pro (quite old, but it has NFC). I entered 16 satoshis on the green screen, and then pressed 'Charge'. The black and white screen with the QR code and 'Scan or tap to pay' came up
With cashu.me open my friend's phone, we put it on top of my phone. Eventually, I got asked to choose between one of two options (If I remember correctly, something like 'Cashu Payment Service' and 'Phoenix ...'). I selected the Cashu Payment Service and then I got this screenshot
I couldn't get any further, either by touching this on my screen, or by moving our phones around.

The NFC settings on my phone, the one running Numo:
