Regarding wireless audio, the AptX codec increases quality, but you need a specific variant - "AptX LL" for low latency, so be sure your transmitter and receiver are both AptX LL. And as mentioned above, it's still ~30ms latency, which is just enough to bother my ears a bit.
A possible cheapo option is using a guitar wireless transmitter/receiver as a wireless IEM. It's mono and clunky, but works pretty well.
https://www.youtube.com/watch?v=uXTZNY5Ta-o