Replace with higher quality material with a higher DCOF rating.

" Is there a specific type of Rustoleum (or other) spray can that would work "

No.

Are you thinking of something like the Rust-Oleum additive? We used it on our patio and entry mixed into the clearcoat. I think we used a bit extra than the stated amount for our entry, because of the slip hazard. The product isn't super effective against slipping, but it does help.

Thanks for the info. I have the sand & other gritty material. I want to find a simple way to get it to stick to the top of the paver squares. Hopefully something that would be effective & last for a year at least.

Low Gloss Paver Sealer + Fine Grit Non-Slip Additive

(Products not tested by me.)

You say they're 12" concrete pavers at the base of the steps.... can't you just change out those pavers to something that has better texture / grip? or cover the spot with an outdoor rubber tread / mat?

They are probably 12" patio blocks (1 1/2" thick, not pavers). Typically they are not slippery unless there is buildup on them. Try power washing first.