@Bouke-Ent Just be sure to pick a waterproof one, as that video suggests!
This one seems to have OK-ish reviews:
https://www.amazon.co.uk/TUNAI-Button-Media-Remote-Control-Black/dp/B07JQ8Q6X6
(I'm not endorsing it, I'm just saying it has more than 5 reviews, and they aren't all 1 star. 😲 )
Those Bluetooth media controllers are so common that maybe MRA could create a mapping within the app since the buttons are pretty standard (+/- is up/down, rewind/fast forward is left/right, etc).
Then you wouldn't need the Key Mapper app either.