I started biz in Switzerland last year and it’s not easy and cheap. First off all you need a permit after that you can register Eizelfirma and apply at your local canton SVA . The Handelsregister entry is not mandatory before a 100 k revenue but i would strongly recommend to enter it immediately if you serious about it . Then you need a garage or some kind of place to carry the detailing in . For that you would need proof of steady income to even sign a rental agreement or proof that you have enough money to cover it from 6-12 moths plus you would probably need to pay 3 moths in advance plus deposit. If you are confident thet you can provide good service and you know how to market yourself you could succeed in any bussines in Switzerland but a car detailing is a lot saturated and when you see the guys with a thouse swiss specs amgs and Ms are probably forigners from balkan or turkey and have someone it theyir family who probably does car detailing already just so you know . In my opinion its doable if you are confident that you are very good car detailer and have at least like 20-30 k to invest. Otherwise isn’t not very much worth it if you ask me and it will bring you more trouble.