The pink lemonade is right there on the shelf next to the value stuff, ditto the Bon Maman apricot conserve next to the essentials jam and the vine tomatoes next to the tasteless ‘salad’ variety
Except that they might not be.
People need to be realistic.
The supermarkets have been clear: to keep the supply going they will keep volume up but choice down . So there may very well be only two choices of tonic rather than the usual 17.
Two types of tinned pasta with sauce rather than Heinz plus own brand alphabet spaghetti, Tom and Jerry pasta shapes etc etc.
Last time I was in our supermarket had a reduced range of cereal types and only branded or own brand of each one.
Choice of satsuma and similar much reduced.
Last time I was in a shop there was no fresh milk and no soy milk, only v expensive almond.
Time before that only unsweetened soy milk: tough luck but no big deal for my teen who preferred sweetened.
Of course volunteers will try to do their best but we all need to be realistic.
And it isn’t fair or sensible for society as a whole for volunteers or anyone else, to visit 4 shops for Fevertree Mediterranean Tonic, for example, when Schweppes was available in the first shop. We all enjoyed a G&T before Fevertree was invented 
Realistic, and kindness, tolerance and understanding all round will help.