@Fenevadkan
OpenWrt was/is designed to run on very low-spec machines, with relatively little Flash-ROM/RAM (like the routers you can buy from NetGear, et al). That is why OpenWrt uses dropbear instead of OpenSSH, and dnsmasq instead of (say) knot resolver (and so on). Even the busybox tools are modified to be smaller than ‘normal’ (and busybox was designed to be small).
Howeverr, the Turris Omnia has lots of Flash ROM/RAM and so you can pretty well run whatever you like…
In the case of DNS/DHCP, OpenWrt has for many years used dnsmasq, and that product has been dragged into the current age (e.g. the very recent addition of DNSSEC). It has the benefit of tight integration between DHCP and DNS. FWIW, it can be an authoritative (not a use-case for a SOHO/home router), or a caching-only relay.
For cz.nic, knot DNS came many years before the Turris project.
I am not 100% familiar with knot resolver, but I can confidently say it is pretty industrial. It can be an authoritative server, and you could comfortably use it if you were a TLD operator (and I assume that is the case for the .cz domain). I can safely assume it was never intended to run on a machine with (say) 4MB of RAM (although I am happy to be corrected on this point).
In short, dnsmasq and knot are coming from different directions and our TO routers are in the middle. I think @vcunat may well agree with me on this point?
Nonetheless (and IMHO), dnsmasq is a better fit for OpenWrt/LEDE, but others may disagree…
EDIT: some corrections…