Sandboxing is crap on Firefox (specially on android) . Google is really fucking good at security since they are well a huge multinational behemot. They know security. Security =/ privacy. When you are using android you are using Chrome webview no matter what browser you are using. So just piling on stuff instead of replacing things won't be a good security practice.
Also the Google parts are optional , you don't need Googles stuff to use chromium. Just like vanadium does.
Use a public net /local coffee shop. Or one of the options above. Also No issue running stealth mode VPN ..