What can we do to make flatpaks follow the GTK theme?

Hi guys, basically as the title says. Did any of you guys tried any of the solutions around for this? What is the best fix for this in your opinion?

Edit: Found it! the best way is to install your GTK theme as a flatpak so it is either that your theme is available in Flathub which is rarely the case or running this to automate this process for you