I don’t believe there’s any such thing as “too short to trademark”. If it’s long enough to be a recognisable name, it’s long enough to be trademarked. E.g. the

I don’t believe there’s any such thing as “too short to trademark”. If it’s long enough to be a recognisable name, it’s long enough to be trademarked. E.g. there are UK phone brands called “BT”, “O2”, and “Three”.