After quite a few of the cheaper "kids" headsets never lasting..... 3 from memory all ended up malfunctioning, I bought my son the SteelSeries Arctis 1 wireless in an amazon sale when he was 8. It was one of the better quality wireless versions that worked with the Switch (via Dongle). 18 months on and its still going strong (and we haven't lost the dongle!). It gets used for Switch, Ipad etc and gets carried around everywhere, stuffed in bags, taken to sleepovers and its been fine.
I was wary of buying an adult headset that was more expensive but so far its been a good investment. So much more reliable than the cheaper but more colourful kids versions. I'm not sure if its appropriate for your daughter at 7 but its worked for us.