Thank you so much!
Here's another one that talks about how breeds that lay a huge amount of eggs (like Tally) are prone to health issues... And this sanctuary uses these implants to give their little bodies a break - especially hens rescued from commercial laying:
https://opensanctuary.org/suprelorin-implants-a-critical-tool-in-chicken-health/?print=print
My challenge is finding a vet willing to administer since it is off label here. Used with hens in the UK, but not here in the US. Seems folks who are raising chickens as pets/eggs for their own consumption, not to sell, could get this implant for health reasons.