Isn't your warranty in jeopardy if you change things that you are allowed to change(linux things) from start on Jolla?
AFAIK there are certain things Jolla would not repair/use warranty if you changed in system, so it's same same. And i had jailbroken iphone for few months and was using app store with no issues, not an expert but I think you are not banned for jailbreaking, at least that what was few years ago.