Inspired by my own comment I looked into it again and came up with this combination in the game's "launch options", which feels much better:
DXVK_CONFIG="dxgi.syncInterval = 0; dxgi.maxFrameLatency = 1; dxgi.maxFrameRate = 60" gamescope -f --immediate-flips -- %command%
I didn't know about `DXVK_CONFIG` before. It's the DirectX-Vulkan translation layer with its own framebuffer and latency.I also manually disabled vsync in the game's `local.cfg` XML file.
I love where "gaming on Linux" is going. But I have the feeling the hype on Youtube etc. is in part created by content creators, and doesn't faithfully represent the actual situation (surprise!).