SD card wrong space

[bitnick]

that would be a "better" option if one wants to destroy his/her NTFS volume and all the data it holds. for others, - just don't do that.

Installing, say, Ubuntu on a disk that already contains Windows usually works fine. There is a risk of course, any time you move around or resize partitions. Make sure you have a backup.

for the OP - after you flashed your SD card with the OS image for running on Pinephone, you should not use it elsewhere.

There is nothing wrong with using the SD card elsewhere. Just use it with systems that can handle the file system that's on the card.

It's practical to do the same with USB memory sticks - install a live linux image to it, and then use the card for both storage and as a generic boot stick. Both types of devices are just block devices and you can use any partition type and file system type(s) you'd like on them.