I heard that these days people use the OpenCore approach rather than Clover or other older methods. Does OpenCore make installation easier and take less time?
YES. Learning curve on how to setup the bootloader can be a bit tricky. However, if you watch just a couple of tutorial videos with a system on the same platform as your PC (Skyle, Coffee Lake, Rocket Lake, etc) then it's fairly easy. I use a program called OC Gen X to create the bootloader which generates all the necessary files for me and then I just need to tweak the config.plist file and that's basically it. Just move the bootloader to your EFI folder and you computer will behave like a normal mac.
I've ran OS upgrades and security updates with ZERO issues.
Clover I never liked, convoluted garbage. Unibeast/Multibeast was truly easy but it wasn't perfect and running updates screwed up a LOT of things.
Opencore is amazing, basically everything in my PC works 100%; sleep and wake, audio, all USB ports, etc.
With OpenCore, if you ever need to reinstall Mac OS, all you need to do is copy the bootloader into your EFI partition. There's ZERO setup afterwards.
In the dortania's OpenCore Install Guide, it mentions several ways to get MacOS including from Windows. Is it better to get the Mac OS installer directly from a Mac? I worry that if I get the installer from other sources such as via Windows/Linux and github, those installer may not be an authentic Mac OS installer but a modified one which could steal information from my computer after installation.
It really doesn't matter. It is easier to make a bootable Mac OS install disk via Mac OS though, I'd just do it that way if possible.