Shopify announced on June 22, 2022 that they are finally adding a native combined/stackable discounts option https://www.shopify.com/discounts. I confirmed with Shopify Plus that this will be rolled out around June 27.
I spoke w/ Klaviyo support to see what their timeline was for implementing this in the coupons section and it wasn’t on their radar.
I do no see a plan to add this to our Coupons feature in Klaviyo on the upcoming Roadmap. However, I have submitted this feature request to our Product team to be considered as a feature to be added in the future. At this time I do not have a timeline on when this will be considered or released, but I have submitted this feedback to our team.
Just putting this info out there for other Shopify merchants as this is a pretty big deal.