I've gotten good results with both Pinegrow and Bootstrap Studio. The author of Pinegrow is on HN and might comment if he sees this.<p><a href="https://pinegrow.com/" rel="nofollow">https://pinegrow.com/</a>
Isn't <a href="https://bootstrapstudio.io/" rel="nofollow">https://bootstrapstudio.io/</a> essentially what you are looking for?
not bootstrap but i got links for some wysiwyg here<p><a href="https://jxyz.me/javascript-text-editors-renderers" rel="nofollow">https://jxyz.me/javascript-text-editors-renderers</a>