is OM-5 AF good for video ?

Is OM-5 CAF reliable for video ?
Better than Fuji X-T4 ? Or worst…
How does it compare to Z fc ..

OM-5 has the same AF system as the E-M1 mark 3, so it will be far superior to the XT-4. The XT-4 is notorious for hunting in video. See this video test

Lets not even get onto the topic of Fuji's IBIS rating lies too. Very poor compared to OM-5.

Thanks.
I should rent one and test it.
I need something portable with decent CAF. OM-1 is great but seems too bulky for me, at 599g it is heavier than R8 FF, A6600 APSC.

No problem. Here's actually a side-by-side showing how much better the E-M1 mark 3 (same internally as OM-5) is compared to XT-4 in video.
See here

I think it is just a conspiracy theory :-)