Will RandomX work on the old cell phones, via Javascript interface only?
The website says: "Fast mode - requires 2080 MiB of shared memory. Light mode - requires only 256 MiB of shared memory, but runs significantly slower"
If you want your website challenge to work on the cheap phone - slow CPU, with little memory, and when implemented in Javascript, you'd have to tune complexity way down. And when a modern PC with fast CPU and tons of memory tries to solve it.. it probably will take only a few milliseconds, basically being useless.