This DMT thing looks good. https://smile.amazon.com/DMD-Diamond-Whetstone-Sharpener-Coarse/dp/B08TWLQ5WW/ref=sr_1_193?dchild=1&keywords=knife&psr=PDAY&qid=1624310329&s=prime-day&sr=1-193

I don't know anything about the whetstones for sale, they might be good or not, but they are cheap.