I've used WD40 to clean chains, but it's kind of inefficient and expensive. Lately I've been using gasoline, with great results. I use a shallow plastic tray (like a kitty litter container, about $2-3 at a dollar store), and pour just a little gas into it. Then lean my bike against something, position the tray under the chain, and dip a heavy paintbrush into the gas and immediately rub it all over the chain, allowing it to drip back into the tray. The chain is visibly cleaner after just one wipe with the brush, but I'll do several more. Then after several passes on that section of chain, I'll wipe the chain with a scott towel, then turn the crank to expose another section of dirty chain, and repeat. It's quick, very effective, and only uses maybe a couple cups of gas. Lots cheaper than 1/2 a can of WD40, and in my experience, faster and more effective.
As for using a lube that isn't bike specific (which, along with gun lubes, are largely a sham, IMO), I've seen some encouraging comparison reviews on using gear oil, like this......
https://shop.advanceautoparts.com/p/...hTerm=gear+oil