For simple browser-based protection: Opera browser has a genuinely free built-in VPN, just toggle it on in settings, no extension or signup needed. ProtonVPN’s free browser extension is another solid, no-logs option, I saw this one recommended often for exactly this kind of casual use.
Both cover your two goals: encrypting traffic on public WiFi and unblocking geo-restricted sites, since they change your apparent location too.
One caveat: browser extensions only protect what happens in that browser tab, not other apps on your device. If you’re doing anything sensitive (banking, etc.) on public WiFi, a full VPN app that encrypts your whole device is more thorough.