This is not the only device capable of running GOS for years. Like with pixels, you didn't have to replace the phone every year to keep using GOS.

Just buy something older (ideally version 8 or more recent) and switch to Motorola after few years, when Signature 27 is much less expensive.

That is a different story in that CyanogenMod had a for-profit company funded with venture capital built around it and where the owners flirted with closing the source for selling the OS, who then failed to sell it and sustain 130+ employees. GrapheneOS Foundation is a non-profit, funded for 12 continuous years with donations only, paying for less than 20 full-time employees, with an entirely FOSS OS project whose management actively avoided doing the same thing, despite GrapheneOS being more adept to permissive FOSS licenses rather than CM's and anyone's beloved GPL. CyanogenMod management blamed its hired developers during their fall for "not sharing the same vision" as the company, who decided to sell the OS to OEMs instead of just keeping it there, open for whomever wants to use it, which is what is happening here with Motorola. It's very important to note that there is no money changing hands between GrapheneOS Foundation and Motorola Mobility.

Who supported it?