My understanding is that soap and water is better than sanitiser against covid-19 and
this backs that up (and states 60% alcohol is enough ... but who's going to argue about a bit of extra alcohol?)
As for whether it affects blood sugar readings, I thought I had read somewhere that paramedics use saline to wash hands before taking a finger prick reading because the alcohol
can have an impact.
I appreciate taking soap with you is not as easy as using the sanitiser provided at a restaurant but maybe it is an option to consider if you are concerned about the accuracy of your blood sugar reading when eating out at the moment.