Nate Yea, I made a perfect solution using your options!
I made another shell script in Spine directory which runs Spine.sh:
cd "${0%/*}"
nohup ./Spine.sh
While adding &
into last line inside Spine.sh itself
This way it's possible to launch Spine using .desktop file, it doesn't even show terminal and doesn't print any nohup.out file (which is strange for me, but it's the ideal situation smh, because I don't want to have constantly growing file with kinda useless text in my home directory)
Many thanks!