[rudiv]

Have you tried 19.10 or 20.04? Before that I had a lot of issues with my Dell XPS 9560 because of optimus, but it got a lot better in those versions. YMMV but it actually worked out of the box with nary a hint of manual configuration when I installed 20.04 recently.

Edit: should note, when I say work I mean you can switch between GPUs/launch an app on the dedicated GPU with ease.

[Sangeppato]

I've tried 19.10 and Arch Linux and the only option still was to statically choose only one GPU and reboot. How does the offloading work now? I haven't heard anything about it

[hvis]

19.10 added the "NVIDIA On-Demand" profile in Nvidia Settings. It needs the driver version 435 or newer.

It works okay, but you have to launch processes with a specific set of env variables to use the Nvidia card.