[ROM][UNOFFICIAL][8.1] switchroot LineageOS 15.1

You’ll need to use hekate. SX OS is only „good“ for one thing, and that’s not booting Android

Sitting at 20 minutes on my SD card with a black screen also. Guess I'll have to scrounge around for another card.

So, how do I copy files from my PC to Android's "Data" partition or "Internal Memory"?
MTP in TWRP does not work,
MTP/PTP in Android does not work,
FAT partition is not visible in Android, also it's too small anyway,
OTG in handheld does not work, so I'm unable to copy files from pendrive either.

So what's left? USB on dock, or transfer via network, right? Anything else?

SD card type definitely plays a part in loading times as it runs completely off the SD Card, I am in the same position I've just tried a 16GB SanDisk 10 (UHD I) but took about 30 minutes to boot, so trying a 128GB Samsung (UHD III) I had in my Chromebook to see if its any better.