I attached a draft of a screenshot. What do you think? Something interactive like that where you can practice an action again and again?
But how will you learn if you don’t make the mistakes we all learn from?
Besides, you can practice installing a spark plug a million times, but when you get to the real car and the first thread is bunged up, what then? Do you get free access to the AP of “how to use a ‘backout tap’”?
I don’t see how it’s any better than watching one of a thousand available u-tube videos and being able to pause/rewind/replay over and over to my hearts content.
What does that screen shot depict that would actually be useful to auto repair?
I think the attachment is meant as an illustration of a existing app, not as a picture of a home page for an as yet uncoded automotive app. Unless it’s for a robot body welder!
It’s an illustration to show the concept. And an app is better than videos because you’re doing it vs. watching it done.
One problem I can think of is that until we get VR sensation gloves, you have no way of simulating what it feels like to put things together. After working with cars long enough you get to know by feel when something that doesn’t have a torque spec is too loose, too tight, or just right. You can also feel when something isn’t going in right, is cross threaded, etc. Without that simulation someone could very easily think they knew how to do the job because they’ve clicked on the part over and over again in your app, but don’t actually know what to look/feel for when doing the job.
Another problem is that assembly simulations are too clean. It’s very easy to practice removing exhaust bolts on a tablet. It’s very hard to actually remove exhaust bolts without breaking something unless you know how to do it and are very patient and have the right concoction of noxious chemicals to loosen those rusted, horribly fused bolts.
Your simulation would also need to cover all possible contingencies. Doing brake work? Well, OK, you need to know what to do when you take the caliper off and accidentally drop it, and it yanks on the flex line which cracks the hard line (not that I have ever… Uh… Had that happen. Nope. Never!)
And you need to know, now, how to replace that hard line which often involves custom bending a stock hard line – because if you don’t know, you’ve got the stupid thing disassembled and it can’t be driven so you have to pay a tow truck to take it to a shop and then pay the mechanic to fix your problem for you, which is both expensive and embarrassing.
And an app is better than videos because you're doing it vs. watching it done.
Not really. The reason I am watching the video is because I’ve never done it before. I want to watch someone who has, perform the work so I can see the order of things and even more importantly hear their commentary on what to watch out for.
Your competition is tough. There are apparently countless people who have the time to document just about every repair known to man. I can watch half a dozen people (some pros) do a job and glean the best info from all of them and it’s completely FREE.
It used to be, the worst thing a paid repair person could do is say yes when I asked if it was OK to watch. Now I rarely even need to pay the apprenticeship fee 
I’m sure an app would help a lot of people. Everyone learns differently and apps can be very useful. Those of us approaching geezerdom need to realize that the times they are a changin’… 
No better way to learn than screwing up a few times. I remember as a kid breaking off small engine head bolts, stripping threads etc. You learn touch pretty fast.