Nothing new here. E2E is only available in one on one chats and is disabled by default. Dont use Telegram if privacy is your main concern.
At least it has an open-source client. Very few messaging platforms can say that, and fewer have a decent UX.
It’s not perfect, but it’s got a good combination of features and multi-platform availability. None of the other messaging apps support all of my devices except Matrix, and Matrix doesn’t have stickers
Edit: Signal doesn’t support all my devices but maybe someday! The network effect is also big. None of my family and friends are on Signal, but most have Telegram. A few have Matrix.
Also Signal is a US-based company.
Edit 2: Matrix does have stickers, i guess I’m switching
Probably a bit better than Windows but ultimately with Apple you can’t know for sure. Their software is proprietary and closed source, so it cant be properly audited by a third party.
Apple can claim whatever they like about privacy, it comes down to whether you take their word for it or not. Personally, i think Apple has been caught being dishonest about their software more than most tech companies, so i take their claims with a heap of salt.
If you want something that can actually be proven to be secure, the only real option is an Open-source (and ideally FOSS) platform. Anything that can’t be audited can’t really be trusted.
For a laptop or desktop, Ubuntu is a safe, secure, well-audited option. Mint and Fedora are also good options for most hardware. There are good DAWs available on Linux but perhaps not the exact one your friend is used to.
I would suggest anyone new to Linux to back up or remove their ssd, and install Linux on a second or new ssd to reduce the chance of accidentally wiping your data. A new OS is like getting a new computer, and you need to save your data externally before you start the process.
Edit: I’m aware that some parts of macOS are technically open-source, but that’s almost meaningless from a security perspective when critical parts of the OS aren’t open. Darwin being secure doesn’t make the whole OS secure when network manager is still a black box (for example)