I found that tepache was simple and interesting...And there are a lot of differing opinions on some of the details. I think the thread is a good read-through. You see some experiments and tweaks.
To answer the scoby question, no, there is no scoby. I have, however, gotten a covering that I guess is a "yeast raft". Using a bottling bucket, I could draw off the tepache from under it and it never seemed to be a problem.
I did NOT like the flavor of adding a beer to the recipe. I did NOT waste the pineapple flesh...Eat it! You only need the skins. I also use the core. Toss the top/leaves and bottom. Rinse the skins, but don't scrub or sanitize... they are providing the wild yeast.
It's been awhile, but, as I recall, I think I used an airlock from start to finish. I know it was always covered. After a couple days, or a little longer, the solids are strained. Then you ferment to your preference...A week longer was usually about right for me. If you want extremely low alcohol, go less. If you want more, go longer. I guessed mine was generally around 2-3% ABV.
It's good over ice, mixed 50-50 with a lawnmower beer, or lemonade. Great for Summer, because it ferments better in warm weather and it's a good drink on a hot day.
I have pretty good notes in a blog, if you are interested and I'm happy to answer any questions. I'm certainly not an expert, but I did make several batches a couple years back...Maybe I'll make some more this Summer. I haven't been active here recently, because I have brewed since last Summer and life has pulled me in another direction, but you can pm me and I should see an email notification, like I got from @passedpawn. Cheers!