Travel routers with VPN or Tor allow you to avoid trusting the DNS from WiFi ISPs and cell phone towers. Some even let you plugin USB modems and switch MAC addresses to help bypass WiFi captchas on multiple devices. This article compares GL.inet to a Rasberry Pi with OpenWRT, and can give you some ideas for privacy and security for whatever choices you make:
A second Android phone running lineage or calyxos is a excellent travel router. These OSes allow you to share the VPN via tethering.
Also, if you’re worried about GLI.net’s software, you could just install vanilla open WRT on it.
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The commentary on telegram confused me. If you’re worried about telegram requiring SMS authentication for new accounts, running a telegram account across a VPN across tor doesn’t change that. Does it?
Author of the article I believe meant the end user was using a crypto-burner SMS verification, such as the ones on this list: https://simplifiedprivacy.com/burners/
Then combined with Tor is fully anonymous. It depends obviously on what you want to achieve
Do you know if all models are compatible with OpenWRT vanilla firmware?