Hey, I run Nocode.tech and can probably give some advice here - No perfect answer sadly but a few to try
First, Worth noting you can export Webflow as code and rehost it wherever you like if that’s helpful. BusyWorkHQ hasn’t launched yet I don’t believe, but it’s a backend builder for Webflow and may help you solve your problem by letting you connect a database/api thru to Webflow. @PatrickStolc on Twitter is building it
Have a look at Adalo - They have the ability to replace their backend with an external database (it’s a little bit tucked away but it’s there). The downside is that the front end parts aren’t as freeform as Webflow. They’re more focused on mobile but support web apps too
You may also be interested in React Studio, Wappler or UIBakery