Clipping your fingernails or toenails falls into the personal grooming category and should be done in private. Never in public.
Airline attendants recently created a top 10 list of annoying things passengers do. I was shocked to learn clipping fingernails and toenails on board made the list. I’m not shocked they are annoyed by it, I am shocked people would actually do this in public, especially on an airplane.
Please present yourselves as a finished product, not as a work in progress thank you.