Not OP but I've had luck with zinc and magnesium aspartate supplements commonly available on Amazon. I take two caps that each are a net about 500mg an hour before bed, along with 1mg of melatonin.
Been doing this for a lot of years now.
Been doing this for a lot of years now.
Edit, here's a paper by some other researchers: https://www.tandfonline.com/doi/abs/10.1080/0963748012005760...
You basically need to be careful with any supplement since it's unregulated, and need to do a lot of careful diligence. It's a good sign if they are honest about their supplier and you trace back their supply chain. E.g. for many chelated supplements (zinc included), if you see a TRAACS trademark then the source is Balchem (Albion) which to my understanding is fairly well regarded.
ConsumerLabs tested one such TRAACS product and found it to be 0.1 mcg/g cadmium, so likely most products using TRAACS zinc bisglycinate formulation should be similar. I also found some EU food safety application [1] which confirms that across 3 different manufacturers of zinc bisglycinate (one of which is Albion), all samples were < 0.1mcg/g
[1] https://efsa.onlinelibrary.wiley.com/doi/pdf/10.2903/j.efsa....