Increase variant limit for BXGY rewards beyond 100

The merchant would like to increase the current 100-variant limit when setting up reward (Y) products in Buy X Get Y (BXGY) campaigns. Right now, if a promotion involves a large number of variants, the merchant has to manually select them and split campaigns into smaller groups, which adds unnecessary complexity.

Expanding the variant limit or allowing merchants to apply the same targeting options (such as collections, product tags, or vendors) for reward products as they can for qualifying products would make campaign setup much easier. This would ensure customers can select from a wider range of eligible products without the merchant needing to create multiple campaigns.

If you also see value in removing the 100-variant restriction, please give this request an upvote so it can be prioritized for development!