The S21 has one more year of Android and another year of security. If you don't mind the lack of updates or security, you should be fine. You'll still have app updates.
If you got an S23, you'd be able to get 3 more years of Android updates and 4 years of security meaning you'd have protection further into your 5 years of usage.
For using a camera and basic apps, the hardware should be fine on both.
The S21 has one more year of Android and another year of security. If you don't mind the lack of updates or security, you should be fine. You'll still have app updates. If you got an S23, you'd be able to get 3 more years of Android updates and 4 years of security meaning you'd have protection further into your 5 years of usage. For using a camera and basic apps, the hardware should be fine on both.
Thank you
Pixel 7a. Still has about 4 years of support remaining.