[Renate]

The very cheapest devices ($1 selfie clickers) are completely mask programmed and nothing can be changed.

Better devices (BT keyboards) have the bulk of code in mask program and an I2C EEPROM for configuration.
It's quite easy to change the display name for the device to anything (with the same or less characters) as those strings are conspicuous.
The HID report descriptor is easy to find too.
If the Usage for the button is not an array it's easy to change button assignments.
If it is an array you'll have to find the values elsewhere and they could be in instructions instead of raw.
If you want to change other thing (like sleep timeout) it can get complicated.
If you end up doing all this work, buy a case of these devices.
When you try to re-order everything will be different.
Of course you'll need an I2C master running at ~3V.