Best Multichannel App?

I sell primarily through Shopify, but occasionally through Amazon and EBay. I advertise through Facebook and Google Ads. Each platform has various restrictions (like no logos on Amazon, no mention of lighters on Facebook etc…)

I’m looking for a multichannel app that allows me to have different pictures and descriptions per platform and binds everything together to make things simpler.

Can anyone make any recommendations? I don’t sell a million small things, but rather a few more expensive things (my most common products at $350 and $650 each), so any platform that scales pricing based on volume of sales would be great. It would be nice to be able to manage multiple stores, even on the same platform.