dlfantoma Are there any concrete examples of usable exploits for the older ones?
At any given time it is likely that there are many vulnerabilities in EOL devices that are not announced and tracked. My impression is that Google does not publicly track vulnerabilities for EOL devices. So "absence of evidence is not evidence of absence" for EOL devices.
Meanwhile, a disclosure for in-support devices, like the one linked above, acts as a guide for people who want to break into EOL devices. Every 4-series and 5-series Pixel is less safe today than yesterday. Edit: Plus, probably, lots and lots of EOL Samsung, Sony, etc., devices.