"Your security key does not have enough space for any more accounts" - What do you even do in this situation?

I didn’t do a ton of research back when I bought my Yubikeys. I just picked whatever was the most popular. In retrospect, something like Nitrokey or Onlykey looks cooler to me. I like Nitrokey’s open source hardware aspect but I also like Onlykey’s on device PIN entry. I might just wait until Nitrokey comes out with a key with on device PIN entry since I’ve always been concerned about entering my PIN on devices I don’t trust.