Many years ago, I got a "Pressy". It was a little dongle which fitted into your phone's headphone jack. It had a single button on the top. It came with an app so when you tapped the button the app would do something. For example, tap once to open email, double-tap to switch to flight mode, etc.

Most modern phones eschew headphone ports. They let water in, are fragile, and a cheap DAC produces worse sound quality than Bluetooth⁰.

So would it be possible to have a USB-C component which does something similar?

Technically, yes!

• There are USB-C keyboard which plug directly into phones.
• For a couple of quid, you can get mini keyboards with a custom amount of keys
• I can find a single button PTT USB-C device albeit with a ridiculously long cable.
• The Yubikey 5C nano has the right form factor and comes with a (pre-programmed) single button.

I don't have the skills to solder one of these devices myself. So, who makes one?