I did it for my SE and think it’s worth it, I still find it overpriced though.
And I remember having a feature phone with a replaceable battery. Often became difficult to find a new battery after they stopped selling the phone. So if you think the lack of a battery is the only reason you’ll stop using your old phone? You’re probably only gonna get another year.
For phones with user replaceable batteries you'd still need to buy batteries. And there job cost was only a small part of the $79.
Also as I said below if you replace the battery yourself TouchID will stop working as the security chip thinks the phone has been tampered with, so if you wanna keep using that there’s only the official route I think. Not sure about FaceID but it might have the same problem.
I put the old battery in a bucket on concrete overnight because he thought he might have punctured the envelope and I was worried about it catching on fire. No problem recycling it.
It was about $20 for an Amazon battery kit that came complete with tools. Had 20% more charging capacity than the original (when it was new) and my son is very happy with the result. Earphones worked fine, screen worked fine, etc.
(Which is a whole other story that lead me to now own three of them even though I can only use one at present.)
Now I can use the phone for another 1-2 years which is great. I love the form factor as well and right now Apple doesn’t have anything comparable, but I hope they’ll make a small phone again.
Also, the unofficial replacement is not that much cheaper, you get a no-name Chinese battery (which is often worse than the original and more dangerous) and it might break things like FaceID/TouchID because the security chip will be reset and the non-official repair shops don’t have any means to reprogram it (as far as I know).
DPU hasn't been updated for compatibility with iOS 12+, but another tweak "System Info" can show some of the same info: https://old.reddit.com/r/jailbreak/comments/8ecxdm/update_sy...
For me I'd do it at the store because it's the only way to make sure you get a good battery. Most cheap batteries are crap (or at least you won't know if it's crap until it's too late).
If it was possible to get a battery that was 100% known to be original, and I could save a few $ by taking it to a corner shop to have the work done, I'd definitely do that for a phone out of warranty. But in my experience this just isn't possible (which is perhaps a better complaint to direct towards apple than the battery hatch complaint: I want to be able to buy original parts in any shop anywhere).
If the aftermarket battery is fine, you only gain a little. If the aftermarket battery disappoints, you lose big. So it's cheap insurance.