PTFE is a polymer, often referred to by its most well-known brand name Teflon. Over decades of use, there is zero evidence of any health effects whatsoever from PTFE, the only exception being when it's heated to around 500 deg F. In everyday use it is completely inert and harmless.
PFAS is a generic term describing a family of fluorinated chemicals. Evidence is piling up that many of these have serious and long-lasting health effects. Some PFAS chemicals are used as the monomers for making PTFE, but once the PTFE is made, the constituent monomers cannot be released except by extreme heat.
All that to say, your coated guitar strings are completely safe. Certainly safer than the teflon-coated pans I cook on every day.
For acidic foods I use an enameled cast iron Dutch oven, or a SS sauce pot.
Maybe I need to get better at cleaning my strings, I have to admit I do miss the twang of Ernie Balls.