Although our sync with WooCommerce is a direct connection between WooCommerce and QuickBooks, we do support syncing orders from other platforms into QuickBooks - by using WooCommerce as the "hub": pulling orders from those platforms into WooCommerce, which our sync will then be able to sync into QuickBooks automatically.
Recommendations
WP-Lister - syncs Amazon and eBay orders into WooCommerce.
LitCommerce - syncs Amazon, Etsy, and many more channels with WooCommerce
Guidelines
Taxes - it's important to ensure that orders synced into WooCommerce through these integrations use existing tax rules in WooCommerce, so we can correctly sync them into QuickBooks.
Emails - it's important to ensure that orders are synced into WooCommerce with an email (even if it's a random/fake email) so that we can sync these customers/orders into QuickBooks.
Compatibility - although we can't guarantee compatibility with 3rd party plugins like these, the above two have shown to work very well with our platform.