Apps like ShopWith are a good idea. However, what's going to break it is the network effect.
For them to be found, the influencers on whatever medium they are on, be it YouTube, Steemit, D-Tube, BitChute, YouNow, etc, etc then need to tell their audience to install another app and find them on there to purchase "stuff".
It's this extra few steps that limit engagement and incur huge drop-offs. Besides, with YouTube now adding in built in stores and Patreon like services. It makes it easier for influencers on there to stick with YouTube. For the other platforms that I mention, once they start doing the same. Well, the days of ShopWith would be numbered.
Finally, will ShopWith fall fowl of the same problems as Busker.co as they were forced to pay a Google/Apple Tax on purchases through the app and this lead them to close. Having not used the app, I don't know if any purchases then redirect to a webpage to do the purchase rather than on the app. Again, an issue which may cause drop-off points. As genZ may just wish to push their thumb rather than having to fill in a form, which may be a drag.
Disclaimer: I'm in the Ecommerce space and I think of this stuff down to a minute detail. I know all the different verticals and competitors in the space and what they are doing. I don't think I would have accepted them as the next 3 years are going to be very interesting and I don't think they will survive.