The instructions on the 'old' (throat then nose) LFT swabs indicated that if you'd had eg a tracheostomy or certain other issues of that nature, that you could in a pinch do 'nose only'. I have an extremely sensitive gag reflex and checked with an epidemiologist friend who said that as long as I took a good sample, doing 'nose only' for LFTs would be better than a poor sample from a thoroughly-contaminated-with-other-stuff swab that I'd attempted to push to my own tonsils and gagged thoroughly all over.
The new ones - fortunately! - only need the nose sample.