Please be aware that there is a RetroPie version for the Pi0/Pi1 and there is a RetroPie version for the Pi2/P3 models, and they are not compatible between each other, so ensure you download the correct RetroPie version. Byte Knight uses a Pi3, so his image is not compatible with the Pi0.
I am not sure if Byte Knight's theme is available.
Since the Pi Zero only has one USB port, then you should look at the UPCI as it will be a single USB connection with both controllers on it and you will only need to use a USB hub if you want have extra ports available. If you are using a Pi0W, then there is embedded wifi and Bluetooth, so that is less to worry about.
If you follow mr_me's advice and use the GPIO DE-9 adapter. https://github.com/R...es#db9_gpio_rpi then you don't need an adapter for the controllers - unless you want to play other systems - then I'd recommend the UPCI
You don't need a sound card as the HDMI output will have the audio signals in it.
Thanks for the reply & advice. I already know most of this stuff already, I made this design on Thingiverse:
I made about 8 of them a couple years ago & gave them away as holiday gifts. This was before the Pi0w was out. I now Have a stack of Pi0ws. For my FB1 idea, I wanted to design & 3D print a "bracket" of sorts to mount the Pi0W inside, utilize the GPIO for controls. I was going to use the composite AV out of the original FB, but now that you make a good point, why bother when there's the HDMI. Kinda silly why I would want RCA, (I guess I wasn't thinking fourth dimensionally ).
But that does remind me of an issue I encountered with my SNES project. And I'll post my warning here: There are CRAPPY mini HDMI to standard HDMI cables & adapters out there! Beware! Not all of them are compatible with the Pi0 & Pi0W!! As part of my "R&D" for my SNES gift project, I composed a spreadsheet to help myself minimize my expenses. I tried to source my parts as cheaply as I possibly could. I ordered some mini HDMI adapters that simply did not work. I then ordered some 6' cables to replace them that also did not work. Although strangely, they sorta worked on an older TV I had, But the colors were wrong? (& no, it wasn't PAL mode). In the end, I ordered a 3rd round of cables. These from Amazon after a tip from a friend at my local makerspace. I bought the "Amazon Basics" mini to standard HDMI 3' cables. This person even let me use their Prime membership to get 2-day shipping, or else I would've missed my deadline of X-mas. The cables worked great, so If you need to buy some for your "Zero series" Raspberry Pi's, I would recommend them. But just be warned, this was a couple years back, so I'm sure Amazon buys from cheap Chinese vendors, and may have switched suppliers by now, so who know's if they are still any good. I'm just letting people know what ultimately worked for me after getting burned on 16 cheap eBay adapters (which I in turn donated to our makerspace's "purgatory bucket").