My 2 cents:

Unfortunately there is no such thing as low latency bluetooth headphones. I have tried many solutions including Avantree and APTX low latency or whatever that is called.

Does it have to be portable?

What worked decent: “LEKATO MS-1” In ear Monitoring solution on Amazon that you can plug in to whatever you want via 3.5mm - of course you need an USB-C to 3.5mm adapter for the iPad.

I only had issues once when I had too many bluetooth devices in the same room (mouse, keyboard) and wireless guitar solution all on 2.4Ghz was a little too much.

The transmitter gets pretty warm, you need to charge it after a few hours (I don’t know if it is ok to leave on USB charger constantly)

…and of course AIAIAI wireless+ headphones but those are over ears. This solution works really well. But it is not very portable.