I have tried to make a proper Shortcut for quick notes on mobile, too, and arrived at a similar conclusion. The built-in Dictate Text and Ask for Input actions are not designed for typing or dictating an appreciable amount of information.
I eventually settled on using Things 3 (a paid app) as the inbox for my mobile notes. Its Create To-Do With Quick Entry Shortcut action is highly responsive, and can be neatly launched with the action button on the latest iPhone Pro. The (titles of the) notes can be displayed on a home screen widget, which is really nice. Sync through the Things Cloud is reliable. When I’m back home, I review and edit these notes on my Mac and put them in the right place.
This workflow has so far worked perfectly for me. It’s not exactly a journal/daily note, though, as I prefer having one note for each idea or topic that comes to me.