Cool article:
https://analogist.net/post/decoding-radio-ph-capsules-with-rtl_433/
As a former GERD sufferer, this is of interest to me. I would have loved this thing instead of the godawful through-the-nose pH meter you have to wear for 24 hours every 6 months. I would have loved hacking it also 
But, well, I’ll forgo the pleasure of hacking for the joy of not having to deal with that particular condition anymore I guess.