In some sense Thinkpad X200 would fit what you're saying, its modding community is quite active and there are a lot of people selling old parts or parts designe

In some sense Thinkpad X200 would fit what you're saying, its modding community is quite active and there are a lot of people selling old parts or parts designed to upgrade this laptop. Last time I checked the only missing piece was a way to upgrade the display, which didn't age very well (IIRC original resolution was 1280x800 and no HiDPI)