Welcome to the forum @rtp , I just want to express great post !
A few years ago in a thread I posted about Mobirise and feel much if not all of that still applies (aside from perhaps pricing fluctuations). Out of curiosity did you also look at Bootstrap Studio? Why do you feel Pinegrow locks you into hosting and online editing, I’ve never encountered either? Pinegrow is also making a no-code app to be released at some point, it was confirmed by their developers.
The next version of Blocs will release later this year. Not much is currently known feature wise aside from tidbits spread across the forum, but it will have Wordpress support. Also Bootstrap 5 will of course be supported when released.
I’m heading out now but may respond in-depth at a later time. You presented much to read through and assess for properly responding in a quick manner. Again great post, welcome. 