I am from the old school, nothing works better than past wax and elbow grease. A sealant is not a wax, it does not remove any grime embedded in the top layer of the clear coat, but a sealant can be used over the wax finish to prolong the shine.

Don't forget the bottom of the trunk/hatch, the bottom of the inside of the doors, and all those areas you normally don't see.

As for the headlight covers, try one and report back.

Long ago, there was a product called Blue Coral. It came in two parts, a cleaner paste and a carnuba wax cream. It took forever to do my VW, but the shine was worth it. Today I just use Maguire's paste wax, Spring and Fall.
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Keeping it running is better than buying new