My main descktop is KDE but my laptop is gnome. It's kinda an old laptop, Thinkpad w510. I miss kdenlive but want to have a gnome machine for support. How much KDE stuff gets installed if I use the PPA to install kendenlive. Is I dumb to put kdenlive on gnome Ubuntu 19.04. My disk is limited to 240GB SSD. Give me your thoughts please.

It's perfectly fine to install Kdenlive on a gnome desktop. This is what I do.