I suspect your concern is largely misguided, especially for a tiny company like Pololu. As Grant mentioned, we use standard commodity electronic components in our products. At our scale, it is very unlikely that we would have any meaningful impact on rare earth element usage, both in terms of how much might be in our products and how much we can influence component manufacturers.
More broadly, we believe it is better for the world for us to spend our efforts doing things we are pretty sure are good than for us to chase the worry that something we do might have minute negative impacts. We would therefore not want to waste effort on this avenue of "greenness" (or to market our wasted effort, since that would be disingenuous).
However, I would like to know if you know of direct, actionable steps to take to avoid something bad. For example, do you have some specific examples where a component like a resistor or ceramic capacitor from a reputable manufacturer contains some of these elements but an equivalent from another manufacturer does not?
And by the way, Tesla probably has plenty of rare earths in the car, just not in the main motors. Even though they're a thousand times bigger than Pololu and greenness is a large part of their justification, I doubt it makes sense (or that it's possible) for them to design out or redesign every electronic component and small motor and speaker.