"Shedding" spike, potentially for months, is basically confirmed - https://www.jimmunol.org/content/early/2021/10/11/jimmunol.2100637.long (I haven't finished ordering access yet).

I think the most troubling hazard of "second hand spike" is (non-antiviral) immune sensitization - becoming "allergic" to spike, which would lead to antibody dependent enhancement during later viral challenge - or immune tolerance (confusing spike for something normal) (as mentioned last month on my sub https://unglossed.substack.com/p/forever-spike#footnote-anchor-13). Spike alone can potentially prompt formation of syncytia (fused cells). I'm sanguine about possible harms to lungs / gut because those cells can turnover / heal. I think there could be some potential for eye / ear damage, effects on balance, etc. On the bright side, we're surrounded by tons of gnarly chemicals as a baseline so what's one more hazard?