Thats true. Almost everytime GM just wait until I announce my end turn because how varied the action cost are.

Now that I think of it, summoner can effectively get up to 6 actions per round with feats and/or summon spells.

Why do you consider summoner as complex class? Because in-play it is not really anymore complex than sorcerer or investigator.

You can still take a feat from your regular class at level 4, you don’t need to exclusively pick feats from your archetype once you have its dedication.

No. Feat from free archetype has to be from its dedication and it cannot be skill feat. And unless the GM says otherwise, normally level 4 dedication can't be taken with free archetype at level 2 or 4 (level 6 is possible since in certain dedication you can get 2 feat in level 4).

For solo it is best to have open world instead of normal campaign. Because in an open world where there were no specifically decided goal or end, even the GM is playing/experiencing as much excitement/surprise as the player. Roll for encounter, roll for plot, roll for world development, roll for political move, etc. Just roll for everything and decide later how everything connects together.

Writing a book is when you want to present your gameplay in a more coherent manner. Which a standard campaign fortunately is.

If you don't need specific optional rule then pathbuilder is best. But if you need something like no level proficiency then wanderersguide.