As far as I’m aware they can only be used on Android. I did a search for APK on Roku and I all found were some articles erroneously calling custom channels APKs. Roku does let you side load custom channels in developer mode, but you can remove software like you can on an android box, so you’re always stuck with Roku’s ad riddled home page and whatever injects ads into HDMI
I did this to a PNY drive once and they RMAd it for me! I was up front and said it was 100% my fault and I had already had it for a few years. If you’ve got a laptop that has a mounted slot you can probably slide it in to get any data you need off of it