Although ProtonVPN may not directly provide bridges, it would be convenient for users living in places with strong internet censorship to have ProtonVPN over their censorship circumvention proxies, which might not be secure. Routing traffic through those insecure proxies to ProtonVPN will provide their accessibility to the outside internet securely.

Usually, Shadowsocks/V2Ray/Clash, the famous censorship circumvention tools, provide http/socks5 proxies locally. ProtonVPN could connect to the Internet over them.