These kinds of roundabout ways to help the poor always end up with complications that waste time and resources at best, and open up avenues for corruption at worst.

https://taxfoundation.org/sales-tax-grocery-tax-exemptions/

I always try to advocate for KISS, keep it simple, stupid. Want to help poor people? Give them cash. Want to prevent political fighting about who constitutes poor people? Give everyone cash. And then take back based on marginal income/property/sales taxes.