B2B per-customer-tag x per-product FIXED-AMOUNT pricing on Advanced (no Plus, no custom Functions app)

Functions
1

Goal

Migrating a B2B store (~84 wholesale customers, ~hundreds of SKUs) to Shopify Advanced.
On top of standard rank discounts (5/10/12/15% off, automatic, working fine via native discounts),
we need a per-customer-tag x per-product FIXED-AMOUNT price override.

Example:

  • Customer A is rank 15 (gets 15% off automatically → ¥8,500 on a ¥10,000 product)
  • BUT for product X specifically, A’s contract price is ¥8,000 (absolute) — overrides the 15%
  • The cart for A must show ¥8,000 for product X

We pre-grouped the 84 companies into 20 unique price-set patterns (p1..p20):

  • Customer tag: pricegroup:p1 … pricegroup:p20
  • Product metafield b2b.special_prices (JSON), e.g. {"p1": 8000, "p5": 8400, ...}
  • A Function reads the customer’s tag, looks up the product’s metafield, applies a fixed-amount discount
  • Scales to new customers without code changes — just data

What we tried

Built a Discount Function (cart.lines.discounts.generate.run, API 2026-04) +
Discount UI extension as a Custom Distribution app.

On Save we hit:

Shop must be on a Shopify Plus plan to activate functions from a custom app.

This is the official rule: custom-distributed apps containing Functions need Plus.
Public-distributed apps with Functions work on Advanced, but you can’t switch
distribution method on an existing app, and shipping a Public app for a single
merchant feels like overkill.

Hard constraints

  • Cannot upgrade to Plus (cost out of scope)
  • Cannot publish a public app just for one merchant
  • Must work on Advanced

What I am looking for

1. Has anyone solved per-customer-tag × per-product FIXED-AMOUNT pricing on Advanced?
% off apps are everywhere. Absolute-amount overrides per product per tag are rare.

2. App Store apps — has anyone actually used these for absolute amounts (not %)?

  • Howdy Customer Tag Discount
  • Simple Customer Tag Discount (シンプル顧客タグ注文割引, JP)
  • Discount Box (ディスカウントボックス)
  • Wholesale Pricing Discount B2B
  • B2B Wholesale Hub

Specifically: do any of them read product metafields to decide the override price,
or do they all force you to set per-product/per-tag rules manually in the app UI
(which would not scale to 20 patterns × hundreds of SKUs)?

3. Architectural alternatives

  • Discount Codes pre-generated per (tag, product) combo + auto-apply via cart attributes / URL params?
  • Shopify Flow + draft orders for B2B-only checkout?
  • Anything else clever?

4. “Unlisted” public app for one merchant
Has anyone shipped a public app with App Store listing disabled, served install link to
one merchant, and not been kicked off? Is this safe in practice?

Any battle-tested input welcome. Thanks!