Scheduling Price Changes in Shopify Plus where my ERP can't

Question

I have a retail website built in Shopify Plus that is fed by an ERP. A couple times a month at least, I have sale events where some (not all) items get varying levels of discounts (I'll call this my store-wide sale), but my ERP doesn't have the ability to schedule temporary price changes.

I also have unrelated discounts that happen at the item level outside the store-wide sale cycle, so the solution needs to be able these to the store-wide sale price for that item and choose the lower of the two.

I can manually change all my prices with immediate effect in the ERP to start the sale and then manually do it again to put them back to the way it was, but that's time consuming, and normally needs to happen outside business hours. If I change the price in Shopify, the ERP just over-writes them.

Is this possible? Is there a solution short of implementing a PIM that will allow me to schedule my price changes in this way?

I was thinking of potentially keeping my store-wide discounts in a metafield and/or a tag on each item and using a script to do the math, pick the best price, and change the price at the line level in cart and maybe Javascript to over-write price displayed on the PDP and PLP to show that same price.