Catalogue & checkout
Gambio
Variants, tiered pricing (Staffelpreise), vouchers and B2B are on the all-inclusive list, which clears rubric level 3 — but bundles, guest checkout, invoice and direct debit appear nowhere, and 'Zahlungsabwicklung mit PayPal & Co.' is the entire payment story. Nothing on promotion rules, per-channel pricing or conversion features like abandoned cart or one-page checkout.
Shopware
The variant model is the real thing — self-referencing parent-child products with a configurator that assembles property groups and variants, hierarchical categories, unlimited property groups for filtering, and products addressable across multiple sales channels. Payment breadth is thin in the captures: PayPal is the only provider named, and I found no public information on bundles, promotions and vouchers with rules, guest checkout, or invoice and direct debit as payment methods. The checkout itself is documented as customisable without a rebuild via the Store API, payment handlers and the state machine, which is what lifts it above the standard tier.