For information, Michal, the term “hysteresis” isn’t usually used for modern roomstats - it was used for the old mechanical roomstats which were simply “on” or “off”. Modern roomstats typically use TPI control, as described in https://support.salus-tech.com/portal/en/kb/articles/tpi.
So if you go for a third party roomstat, you’ll need to specify one which offers an appropriate cycle time range for your heat pump. I found this article KCS UK which says that variable speed heat pumps typically need 1-2 cycles per hour.
I use a Honeywell T3R which works OK with my 8kW Samsung Gen 7, though I had to reset the cycle time to 3/hour (the minimum available for this stat). The factory setting of 6/hour was fine for my old gas boiler, but provoked unpredictable behaviour in the Samsung MIM controller until I reset it.
Sarah