Check out the video below where I test whether or not the GH5s with Lens Stabilization is useable:

The Tests

Using a GH5 and GH5s with a Lumix 12-35 II lens I conducted a series of tests to see if the internal stabilization on the lens would be suitable for the GH5s in handheld situations.  The tests received mixed results

Conclusion

There are definitely some situation where you can get away with using the GH5s handheld and sometimes where the footage will just be too shakey.  Ultimately – I’d use the GH5s handheld in a pinch, but definitely, prefer the GH5 handheld when given the option.