I am looking for a better router that supports wifi 6 (5GHz ac or acx).
Many of them promise technologies like beam forming that improves performance (it seems that it works like an orientable directional antenna).
I don't know if it is implemented by hardware or is software provided.
Is openwrt compatible with this technologies?
If not, are developers working in it for next realease?
I think the question is not specific enough. If you would ask more specific questions e.g. which technique on which device and with which clients you would like to use an answer for OpenWrt support for this might be possible.
Directional antenna management is unspecific. Tx Beam forming for example is an optional 802.11ac feature. You could also do some research by yourself if your desired hardware may be capable of it.
As nobody knows what hardware you bought and with unspecific questions nobody could tell you about the OpenWrt support status for your secret device.
Beamforming sounds cool, but what it ends up doing is trading speed for distance (by giving up MIMO and instead operating the antennas as a phased array of one stream). Generally you don't want to work users at a long distance from the AP, you should install additional APs instead.
The wifi drivers that OpenWrt uses are brought from the mainstream Linux kernel project. So for the most part you can look there to see which new technologies are being supported on which chips.
Another thing to remember about phased arrays is that you can only steer n-1 nulls or peaks with n elements. Nulls can be strong, potentially very valuable in driving down interference, but you’re only going to get a couple dB more in a peak.