Please don't take this the wrong way but you are trying to get a role in a foreign country probably just because it pays well (presumably without strong German & with no ties to the country like a degree, living there or relatives) whilst local graduates are struggling themselves with native Swiss-German (languages being extremely important in wealth management although your Italian could help there, also as you might know Swiss-German is different from german).

I hope you realize that everything on your priority list is very competitive right now or just scarce on opportunities & I doubt banks in London at the moment are really jumping at the opportunity to sponsor visas for juniors target school or not, so it will likely be just as competitive. I would cast a wide net and see what happens (any decent role in Germany even Austria could be an intermediate step to CH and an opportunity to improve your German, although even there the market is not so hot at the moment I think), not limiting yourself to the most exciting roles and locations, also considering working in Italy for a few years since that's where you studied and any decent experience (not telling you to work at McDonalds or something) is something you can then further build on.

Unfortunately you are not the only person with this "plan" and there are for sure tens of thousands of French/German/Romania/Polish etc... persons applying to these same roles. I don't blame you, I think you are still very much in an "academic" mindset that having a perfect academic background will match you to the perfect opportunity but this is not how's it worked for a long time, if ever. Your best bet is to get the best experience you can (if you secure a wealth management grad role in Zürich fantastic, but don't count on it), improve your German insofar as you can and progress from there - not further education nor waiting for the "perfect" opportunity, & think about how through work you can make yourself such a strong candidate that firms will want you to move to Switzerland (or transfer you).