CAC grading for coins is a good example of something that could work for less overhead too.
Since coin grading, much like cards is subjective, what they do is take already graded coins and they don't even take them out of the slab. They simple certify them with an additional small hologram sticker on the previously existing third party graded holder.
Obviously there would be differences, but it's an idea of how to get started.
https://www.caccoin.com/
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