For reference, here’s the electrical box they tried to nominate:
As others were telling you in that thread @BunnyPkmn , nominations need to be a great place to socialise, exercise or explore. I don’t think you’d show anyone a plain electrical box, or go there to socialise or exercise, so it was correctly rejected. I do sympathise that rural areas can be difficult for nominations, but they do still need to meet at least one of those eligibility criteria and no rejection criteria.
Do you perhaps have any walking trails that have trail markers? Those are one of the more common things you can find in rural areas.