@GoshGeeGolly said in Pi4, pairing random Bluetooth devices.:
Does installing vice, from source, maybe damage some core dependencies of retropie itself. Hence the weirdness?
No, that shouldn't affect Bluetooth connectivity. Also, why install from source when the binary is available ? Vice is also installed out of the box, so no installation should be necessary.
Would I have better luck with a USB dongle? I do have a pretty decent Asus BT400 I think somewhere, but I'd have thought by the year 2020 the Pi4 might have a reasonable enough chip??
If you have a metal case or an USB3 hdd connected, that may interfere with the wireless chip on the Pi and an external USB dongle may work better. You haven't provided the full details asked in https://retropie.org.uk/forum/topic/3/read-this-first, that would have helped diagnose this faster.
Try removing all Bluetooth connected devices from the RetroPie-Setup configuration, then re-pair the controller (I assume 'dual sense' is the new PS5 controller) and see if it works better.