Would it help if we reframed it? What if it were an aircraft? Fully operational, nothing visibly wrong, but one that is no longer maintained? How many months would it be before you'd refuse to board?
Or how about something less dire: you find an overlooked package of ham at the back of your fridge. It looks and smell fine but it's 6 weeks expired. Would you make a sandwich with it?
What happens in 2025? Would you be just postponing inevitable while feeling inadequate/compromised the entire time? (P7a EOL is mid-2028).
You're here, implying you've considered questions regarding privacy/security. And even though spending money on a new phone could be quite demotivating to many, I see the options as either doing it "right" with 7a+GOS or later, or, not having a phone.
Here's Naomi: yewtu.be/watch?v=c48mGsFyCjw
First point. Quite poignant.
Consider that her interviewee's advice is to folks with run-of-the-mill tech, not those with any interest beyond lowest denominator.
Hope this helps you decide!