I would definitely contact your local Trading Standards for advice. If anything was to happen to a child with a taggie you had made you would want to ensure you had covered your bases in every way and TS are good for that. I also think you should check the word “taggie” as I’m sure I had read somewhere that that name is a registered trademark.
From my experience when I made toys, if the charity are buying from you to sell on as their own item, they then take the responsibility for safety on so they would need to check with their insurer on that aspect.