Youโre ok as there is a Germany - Thailand double tax agreement which prevents you from paying double tax. You can continue to pay tax regularly in Germany ๐
Itโs possible as an investor. But there are many coffee shops in tourist areas I have a friend who opened a coffee shop and struggled due to high competition. Whilst there are also many, I have heard visa / tourist businesses can be profitable with the right staff. Good luck ๐
If you can demonstrate an income of around $85k and proof you can complete work remotely you at least have a decent case but I would speak with a visa agent for more info mate