Prussia never joins Germany

[Homer]

It appears like an important reason behind Bavaria leaving Napoleon in 1813 was ambitions to play an important role in post war Germany.

Probably.

The Congress of Vienna 1815 would anyway be the perfect POD for changing German unification. IOTL, Prussia grew INTO Germany, whereas Austria grew OUT of it. Looking at the map one can clearly see that a Germany without Prussia after 1815 seems nonsense, whereas a "small-german solution" seems geographically, and ethnically, reasonable. Thus to get a unified Germany without Prussia, I'd recommend a change in the treaty of Vienna 1815:

Prussia gets the whole of Saxony, but nothing in the Rhineland (or only very minor territories). Venice becomes independent again, so does Milan under some Austrian prince. On the other side, Austria keeps (parts?) of its Netherlands. The German parts of Tyrol is lost to Bavaria, the smaller austrian territories in South-West Germany are also lost. For these, Austria gets the former bishiopric of Liege and the Rhineland. Westphalia becomes independent.

Such a peace treaty in summary means that Prussia is a solely eastern German country, whereas Austria is a main power in south-east Germany AND West Germany. Thus Austria grows INTO Germany and Prussia grows out. Austrian chances for industrialization are increased due to Belgium and the Rhineland, Prussian chances are decreased. Economic unification of Germany is crucial for Austria, but much less so for Prussia. In effect, the roles of Prussia and Austria are changed ITTL "simply" by a singel POD in 1815.

 

[MariaTheresia]

Congress of Vienna

That works. Later opinion in Vienna was that Metternich gave Germany away at the Congress. I don't see Austria keeping Belgium though. It still goes to the Dutch. So could the settlement look more like this?:

Russia takes Prussian and Austrian Poland and sets it up as a wholly-controlled Kingdom (Congress Poland). Could this spell trouble down the road?

In return for its Polish lands, Prussia swallows the whole of Saxony, thereby removing a jealous rival and enhancing its position and prestige greatly in North Germany. The Saxon King is compensated in Tuscany which the Austrians cede.

In return for Galicia-Bukovina, Austria takes the Rhineland and Westphalia. It cedes Lombardy to the Sardinians. Venetia reverts to independence though the Quadrilateral is garrisoned by the Austrians.

As you suggest might this arrangement cause Austria to pursue customs unions with its South German neighbors causing a North/South splt in unification development?

 

[Susano]

With the Napleonic wars ending in late 1813 by Bavarian-Austrian action, the British and Prussian roles will also be smaller (sans 1814 and Waterloo) and the Prussians will be unlikely to gain all the rich territories she did in OTL 1815.

I disagree. Vienna was all about restoration and balance of power, and so it will be again in most alternate forms. And Russia will back the Prussian claims (lest Prussia starts to covet now-Russian Poland), and a Russian juggernaut steaming up Europe from the East is something nobody wants. WHich means, even if Bavaria does get more lands than IOTL, it will still all be about Prussia vs Austria.

And Homer, speaking of the Russian juggernaut... yeah, sans a crippling plague or something equally surprising, Russia will most likely get Poland, end of story.

 

[Kneze]

I was thinking about Germany forming into this map more or less

PS I know got the Brandenburg boarder(among other things) wrong if you can fix it please do

PPS The Reason the German tricolor is vertical is Germany has stronger ties with France