I am not sure about the law, but wouldn't products that are regarded as fanmade or unofficial (like rust awesome repo) come under their trademark policy?
Technically they’d be in violation of the existing trademark if they were using the Rust name for financial gain. The new proposed rules don’t change much in this regard.
https://foundation.rust-lang.org/policies/logo-policy-and-me...
If they’re not commercial and aren’t trying to appear official, then they can most likely get away with just having a disclaimer saying they’re not endorsed or affiliated.
Intent and the effects of use are very important.