Hey friend, went through this myself recently! Here's a place that has bamboo toothbrushes with castor oil bristles. It was my first time trying either material, and the strength of the bristles really surprised me! You can get pretty rough with them and they won't bend out of shape like nylon does (although they're very easy to dye if you brush too soon after eating! 😅)
I think the handles are a great shape and very water resistant. Although to be honest, when time comes to replace mine, I'll be looking for one that has a better overall "bristle shape" (unsure what to call it) because it's really hard to completely brush my molars because of my gums shape back there. Will look for one that points outward at the end to reach back there properly. But these are a great start imo!
(edit: Sorry, realized after that this is for buyeuropean. I have no idea where these are manufactured currently, but I have no alternative suggestions atm)