I’ve worked on similar API setups with Shopify’s Inventory API and can help you connect your suppliers’ systems so stock updates sync automatically and reliably. If you’d like, I can take a closer look at your suppliers’ API docs and give you clear guidance on the best approach and cost before moving forward. Feel free to connect with me.
This sounds like it would need a custom script / app. You could check out something like gadget.dev, which is sort of like a low code tool for creating Shopify app. It’s a stretch, but you could also check out some of the apps that handle inventory feeds and if they’re basic enough they might work