Probably wifi, I dont think Moonlight Embedded uses much ram. I also get the undervoltage warning nearly constantly, since the a+ is powered by the usb port of a projector. Maybe that also affects things.
I use Moonlight Qt on a raspberry pi 5, and used it on a raspberry pi 4 before that. Both connected via ethernet, streaming at 150 mbps. It works very well, feels like being at the computer. It feels like there is next to no delay, and moonlight reports around 5 ms.
Somewhere else I use a raspberry pi 3 A+ with Moonlight Embedded, connected via Wi-Fi, and it works pretty well, but I can notice the delay a bit more. Still able to stream at 40 mbps.
I use Quadlet, which is now merged in podman. The only issue I had with it is running system systemd services as other (rootless) users, I can’t get it to create cid files that the users can access. In those cases only, I have to modify the generated services files, which defeats the purpose.
Podman, rootless containers work well, and there is no central process running everything. I like that starting containers on boot is integrated with systemd.
Kobo ebooks are the best for this, just plug them in a computer and they act as a USB key. Calibre can manage them too. Some models have a SD card slot for a lot more storage too.
Probably wifi, I dont think Moonlight Embedded uses much ram. I also get the undervoltage warning nearly constantly, since the a+ is powered by the usb port of a projector. Maybe that also affects things.