The first thought is on maintenance and support from Google/Facebook compared to someone like Ionic. One of the things people don't think about before it's too late is support, and Ionic is unique in mobile in that we actually make money from supporting our technology directly for customers. We have direct support available for our auth/security/data storage plugins, cloud services, and open source projects. We literally will respond to customer support tickets and make fixes/patches on a weekend if we have to.
Is there any other company out there doing what Ionic is in mobile? You mention having issues with the Web View component, is Google or Facebook ever going to prioritize your issues? It's not likely, they don't have that kind of business model around their technology like Ionic does. Facebook builds RN for itself, and who knows what Google's end-goal is with Flutter (drive GCP adoption? push its ad network?) but it's certainly not to monetize it through dedicated support for the most significant users of it. I'm proud that the Ionic stack is the most user-aligned offering out there because we're literally in the business of supporting and extending users of our OSS stack.
On the Web View side, we've recently shipped one of the first mobile micro-frontend projects in the ecosystem called Ionic Portals which is basically an awesome Web View component powered by our tech and expertise building web view experiences on mobile. Right now it doesn't have RN or Flutter bindings but we are working on them this year. This has been a pretty interesting shift for us and we're now working with traditional native teams not using the traditional Ionic stack: