I use these, cheap and I test them when they come in over the years I've only had a handful be inaccurate.
> hygrometers
Goabroa 12 Pack Mini Small... https://www.amazon.com/dp/B08HWG68TG?ref=ppx_pop_mob_ap_share
Goabroa 12 Pack Mini Small... https://www.amazon.com/dp/B08HWG68TG?ref=ppx_pop_mob_ap_share