What is the ruling on trading gold on a Forex platform that does not charge interest on loans or overnight positions, but rather a trading commission?

What you mentioned is not sufficient to permit dealing in gold through the platform, because the point of contention is the absence of real or constructive possession (qabḍ) in most cases. This is because in the sale of gold for gold, or for silver, or for other currencies, the two substitutes must be taken possession of during the contract session, either actually or constructively.

Constructive possession is realized by designating the gold bar and enabling the buyer to dispose of it, or by taking possession of a certificate that represents ownership of a specific gold bar, distinguishable from others by numbers or distinguishing marks. This certificate must be issued on the day of the contract formation by legally and customarily recognized entities that authorize the buyer to take physical possession of the purchased gold bar whenever he wishes.

There is another prohibition, which is what is called financial leverage, and this is considered a loan that brings benefit. If these prohibitions are removed and the Sharia controls are met, then there is no objection.