Yes, there will be some limitations to using the Ecwid Venture plan with Printful.
When using the push generator, prices are set for the product and can't be edited for each product variant individually. Once a product is created, prices for each variant can be manually edited in Ecwid.
Hats, mugs, totes, pillows, and beach blankets can't be added with the push generator. You'll have to first create these products manually in Ecwid, then manually sync them in Printful. Note that Ecwid products will only import to Printful if they have combinations (variants). Check out this video on setting up product combinations (variants) in Ecwid.
Automatic stock updates are only available for Business and Unlimited plan users, but not Venture plan users.