Passing in a user input to look up the field with that value in a different type

I’m super new here and working on my own app and thrilled about the potential! I’m hoping ya’ll can help me get past a challenge I’m having with looking up data from one type to another.

The part I am working on is setting a price for a Thing of Type Opening based on a lookup in a separate table by a user input variable.

I have a “pricing” Type set up that has a separate row for each product, identified by a productID and with a Field for different sizes (24, 30, 36 inches). This data is never changed by my app - I am manually entering rows in the database as an admin.

During the user flow, they specify a size (Openings - Input Height) that gets saved to the HeightMeasured field. The Opening has a ProductID field that is set when it’s first created and empty Fields for the pricing for each ProductID.

Challenge:
When each Thing of Type Opening is created, I need to set the value of the Field Product1Price to the value in Type Pricing of the Field that equals the user’s input in Openings - Input Height in the row associated with the ProductID from Opening - Field Product1ID. How do I pass in a value for the field to use, rather than choose from the existing list?

For example:
Opening: Product1ID = Product0001; Input Height = 30;
Pricing: ProductID = Product0001; 30 = 19.8
Opening: Product1Price = should be set to 19.8

Can you please help me with the expression/logic to do that lookup? I currently have this but I can’t figure out how to replace the “30” which is one of the field names with the value of the InputHeight