Is it mandatory if I only target Switzerland?

If you use Google Ads, yes. Google applies this rule globally to protect itself legally (Digital Markets Act). Even for a small Vaud business selling only locally, without Consent Mode, Ads performance will be limited.

Is the cookie banner mandatory for a 100% Swiss site?

Technically, if the site does not process any sensitive data and does not engage in high-risk profiling, the nFADP does not always require an explicit banner. However, marketing tools (Google Ads, Meta Ads) require it in their terms of use. De facto, it is therefore mandatory for any commercial site.

Is a CMP enough to be compliant?

No. The CMP must be connected to the rest of the site (tags, analytics, CRM) to actually block non-essential cookies before consent.

Will I lose data by enabling it?

On the contrary. If you do nothing, you lose audiences. By enabling it (especially in Advanced mode), you allow Google to model the data of users refusing cookies. It's a net gain in visibility.

Can I use a free plugin for compliance?

It is strongly discouraged. Free plugins are rarely updated in real-time with legal and technical developments (cookie list, TCF v2.2). A professional CMP like Cookie-Script automates the scanning and preventive blocking of cookies.