Citizenship may take longer but you can for sure buy investor visas

It can be with millions of dollars.

With millions of dollars, you can buy convenience passports in e.g. Kazakhstan or Bulgaria.

Not the most powerful passports in the world, but enough to get visas for a lot of Western places.

Several Caribbean Commonwealth nations are selling citizenship for around $300k USD. Typically this gives you visa on arrival access to western nations.

Looks like Dominica reduced costs to 100k or 200k in real estate.

Indeed. However it can be bought in many other cases. Malta (full eu member) essentially sells citizenship for about 600keur.

"What price would you put on a passport? - BBC News" https://www.bbc.com/news/business-41013873.amp

"Everything you need to know about the Malta Passport" https://www.globalcitizensolutions.com/malta-passport/amp/

Since Malta is part of shengen space, a Maltese passport is highly valuable.

Stowing away wouldn't give you citizenship either. The key objective here seems to be physical access to the target country (to then remain illegally) which should be doable on touristic visas?