I'm not sure why you'd be looking for a data feed product specifically? The reason I say this is because you then have to deal with scheduling and suffer latency when your catalog is out of sync with the other channels e.g. Inventory oversells.
Generally the better approach is to adopt a real time sync product which avoids the issues of a data feed.
If you can provide a little more detail of what you're trying to achieve I may be able to offer some more ideas.
I'm not sure if this is what you're looking for but we have an app, EZ Exporter, that can do custom CSV exports.
We have customers who use our app to create custom data feeds for different platforms such as Google and Facebook. If you need your data feeds updated automatically, you can schedule an automated export as frequent as every 15 minutes.
Our app also has a Dropbox integration and a pretty common setup I see is to schedule an automated export to Dropbox periodically where the file just gets overwritten. In Dropbox, you have an option to create a "shared link" of that file so in case you need that data shared with other people you can simply give them that link.
The downside is it won't be a "live" feed. But if you don't need the data to be live, it could save you a lot time from having to manually format the default Shopify CSV to match the format for each of the platforms you're using.
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