IMO laquering polished aluminium is not a good idea, there’s nothing for it to key to, all it takes is a little chip and water to get underneath and it looks terrible.
Powdercoat laquer is very yellow but a bit harder wearing.
The best I’ve seen is a product by POR-15 and something used by Image Wheels they called ceramic clear coat, which I suspect is the same thing.
Personally I’d just leave it bare, give it a polish up now and again and use a sealant to protect it.