It is not as good as a decentralized system, and even though the server is open source, it isn’t self hostable (technically in an intranet you could but not easily)
But the signal foundation is a non profit with external audits and a proven track record with law enforced requesting data and getting basically nothing (If i remember correctly they only have your user to phone number relation and the last time you were online)
So although it is imperfect, it is an amazing solution that is almost the only 1:1 competitor to whatsapp/messenger/imessage that is privacy respecting, so I am very grateful for it’s existence.
Just like any foss project, there some level of trust if you are going with the main distribution. In theory you are correct that not much is stopping them from releasing a malicious update, but because it is open source, soon enough people would notice that either they released new code that is malicious, or that the new version does not match the source code. That kind of scenario is known as a supply chain attack.
Since the code is open, you can literally read it for yourself to see exactly what the apk does. You can also fork it and modify it however you like, just like the creator of Molly did (Molly is a fork of the Signal client that adds some security features)
Put an nfc tag there, you can insert it behind the leather. Write the same key on it and that way you could tip your hat onto someonea phone for a quick transfer for later communications.
With the way you stitched it, you could easily push one of the flat flexible ones there without having to mess with the stitches
It’s all good, especially now that they have proton.me when it was protonmail.com I had some issues saying it over the phone as some people didn’t understand and it is long to spell.
The computer probably has local security tools (such as an edr) that spy on you any way.
You need to assume it is completely compromised.
But… assuming this isn’t in violation of your company computer usage policy (which it very much might be and can put you in trouble) you can install any VPN (avoid spyware shit) and a different browser (ideally something a bit obscure, like librewolf) and this will bypass the MiTM as the the device that does the MiTM would be either:
A) a network device that hijacks the HTTPS requests (VPN bypass this)
B) the browser used by the company
C) some other kind of software that atteches itself to all browsers via admin installed extensions (obscure browser might not be recognised by such software, be sure to check the installed extensions after letting the browser run for an hour)
And once you are done you can check the certificate chain in the browser to confirm.
Just the fact that it costs means that most people won’t even consider it, making it very hard to recommend.