Self-employment as US citizen

Does anyone have any experience with self-employment as a non-EU (US citizen) B permit holder (familiennachzug berechtigt zur erwerbstätigkeit)? I am looking into working as a pet sitter and dog walker but have read how difficult it is to set up a business as a third-country citizen living in Switzerland.

Is using an umbrella company the easiest way to go, and if so, do you have any inexpensive recommendations?

Plan to apply to SVA Aargau for self-employment status, at this link:

https://www.sva-ag.ch/gt

It is possible that they will wait to approve it after you have invoiced several clients.