Unfortunately, we're not able to set up this loading screen or PDP-style interaction on Replo.
I believe the loading screen was built with something like ClickFunnels — especially two-step order flows with built-in urgency mechanics. ClickFunnels supports progress bars and faux scarcity loaders via their funnel scripting and templates.
As for that PDP style, we're able to support everything except the forms that take customer/payment information. That part is all handled by Shopify's checkout.
Hope this helps!