Both of these headbands that they sell on their store are for round cup Hifimans. The egg-shaped ones need substantially longer arms. At least when compared with the HE400SE which is the only round one I have, the dimensions are quite different and the headband off that certainly wouldn't fit the Edition XS.
The Hybrid Headband is the headband for the Sundara. The Newly Enhanced Comfort Headband is for the HE400i V1/HE560 V1. These are both round cups.
There is also an issue with the latter that it uses pins that click in rather than screws like the Edition XS uses.
I am pretty sure an Ananda headband would work, if you could get that. The cups on that measure identically, the position of the holes for the arms are identical, and they seem to use the same screw-in mechanism.
There is still an issue over the threadlocker/glue used on the screws, how you'd get them out. I have seen reports this is very difficult without breaking the cups.
There is also a $35 suspension headband sold on AliExpress that looks similar design and is advertised for the Ananda, but all the images I have seen with it are with round cup Hifimans, and they don't have top clearance. I don't think it actually fits the Ananda (or the XS).
I looked into this when I first got them as they were just incredibly loose, I ended up
bending the yokes and using a headband cover which improved it to the point they are now perfectly comfortable for me.