Not quite sure what you mean by "restore" but in the past I have bought digitizer + glass on eBay, used my electronics toolkit to take phone apart (holler iFixit), swap pieces like mic/camera from old to new, and reconnect/pop new screen on.
I will say that at-home repair was way more cost effective in the iPhone 3/4/5 era where there was less competition from repair shops. You could buy a $20 screen online and an hour of work saved you $120. Now with costs to farm out repair closer to $80 around here and screens costing $30-40 on eBay, it's almost not worth the hassle of buying/waiting/taking apart/putting back together/etc.
One other thing -- buying screens from China on eBay/Amazon/wherever is a bit of a crapshoot. Everyone sells stuff as OEM but you don't know if it is actually OEM and/or if it is a "second." I've gotten a few dud digitizer/screens which have been replaced for free by the seller, but it just adds time/energy to the whole process. If a kiosk or shop gets a bad one, they just toss it and move on to the next in their inventory. So also worth factoring in.