I was quite surprised to read of the actual tasks you need people to do, not what I had imagined, so you need to spell out exactly what help is needed, breaking it down into specific tasks.
I volunteer for Citizens Advice. I started soon after I retired, and I enjoyed the training, keeping my mind busy, meeting new colleagues, both staff and volunteers. It was incredibly well structured, with very high professional standards. There was a lot to get your head round but I was up for the challenge.
The clients come from all walks of life, including some who are homeless. I have only once felt unsafe with a client, but there is a panic button and staff around. I am currently working from home, and limit my work to an aspect I am very familiar with. I would not want to wfh taking random calls.
It seems to me there will be people with a few hours to spare who might volunteer for one of your specific tasks eg delivering food, filling in claim forms, admin, catering etc, rather than a lot of hours doing a variety of tasks. I hope you are successful in finding some. Or are there any schemes you could enrol with to give work experience, Kickstart, perhaps?