Hi. Specific to your question, never been asked for proof of vaccination, but I have it so maybe one of those, if you have it, they don't ask coincidences. If it is about the money you can get jabbed at LIM over by domestic arrivals for $30. If about unnecessary vaccination , I understand, but it is good for many years, and if you plan to travel more...
On LAN domestics I have asked about a mid-morning beer,
she hesitated then went to fetch one. I find the LP FAs try to please rather than say no.