Headphones

I'm using this: https://www.amazon.com/dp/B00BJ17WKK/ $20 cable with an in-line mic

with these: https://www.amazon.com/dp/B00ENMK1DW/ $70-80 pair of Philips open-can over-ears.

This means you can hear right through them. Sometimes a positive, sometimes a negative. When the mic or cable gives out, you can pay $20 to fix your $100 headset.

I don't know if either of these products suit your purpose, but it was a neat solution I found on another platform a while back and think it may be worth suggesting here.

I am making assumptions about the layout of your TRRS plugs, so it may still not work... be warned.

Your best bet here is to buy a dual TRS female to single TRRS male, specifically one with labeled headphone and mic inputs. The TRRS male from your headphones will have the second ring, the headset mic (TRRS), shorted to ground (S) when plugged into the headphone side of the adapter.

For the lav mic, the TRRS male layout is harder to predict, so using the included TRRS female to TRS male barrel adapter and plugging it into the mic-side of the dual-female-single-male adapter.

The expected behavior would be your headset and lav mic behaving like mic-less headphones and a TRS mic, consolidated into one TRRS male plug as a "headset." This is jank, but is a setup I have used myself. Ideally, you'd be able to buy a TRRS to TRS adapter for the lav mic separately, as those barrel adapters really suck and break too easily.