Fair enough, but most people get a Mac because they don't want to mess around with ripping apart hardware or worry about troubleshooting when something goes wrong. They buy one because they just want to get on with their work and not worry if it goes wrong due to the great aftersales support.
I mean, I appreciate it's fun to tinker. But you probably picked the wrong machine if you're looking to get your hands dirty. GPU is non-upgradable. RAM is limited by the four ports. RAM speed and support is limited by the CPU and the socket. Logic Board can't be changed for a standardised motherboard. Cooling system can't be changed, PSU can't be changed. SSD is proprietary.
I know it's hard but you've got to curb that way of thinking a little. A lot of Windows people also struggle with macOS as they're constantly trying to maintain, troubleshoot, and speed it up. You just have to leave it to do what it does and trust it won't go wrong. I appreciate it's such a different way of thinking but honestly, I think you'll just have a bad experience if you carry that Windows mentality into the Apple ecosystem.