Extensions are a huge security risk not to mention increases your chances of being fingerprinted
Whatsapp uses the same encryption protocol as Signal. They might still be able to look at metadata but not the content of your messages.
Telegram uses a halfass protocol. Stay away by all means.
No reason to use it based on the ones you gave. ProtonVPN has a free tier but the other recommended VPNs (Mullvad, IVPN) are just $5/mo
Extensions are a huge security risk not to mention increases your chances of being fingerprinted