I bought the Ram (OEM) five key fob and had it programmed at the dealer. It works great and now I have a functioning tailgate release.
I tried two aftermarket FOBs with local locksmith programming and neither worked. To be fair, these were FOBs the locksmith recommended and not FOBs discussed in this forum. Good news is he didn’t charge me for either. But there was time wasted.
Anyway, based on my experience, I suggest saving the time and hassle and just go OEM. I’m also very happy with the quality of the key from from Ram.