official website http://www.kmu.admin.ch/kmu-gruenden...x.html?lang=en
A sole proprietor company is owned by one proprietor only. Therefore, labour market regulations for persons apply. A residence and work permit is always required to work in Switzerland.
Limited liability company (GmbH)
The limited liability company (GmbH) as a legal entity must be represented by at least one person resident in Switzerland. This can be the manager or a director. Accordingly, this person / these persons need to have a valid residence and work permit in Switzerland.
The second one is an option very used i think but probably too expensive.
EU-EFTA that are self-employed (for example a polish plumber) can notify and work up to 90 days without asking for authorization, but i don't think this would apply to a writer since he's not doing any work in switzerland. anyway https://www.sem.admin.ch/sem/en/home...verfahren.html