Hi I am looking to buy hardware for a firewall that is able to run both OpenWRT and TurrisOS since I want to experiment with both. Will the Turris Shield fullfill this criteria? It it possible to install OpenWRT? I know it’s not on the list of supported hardware but that doesn’t nescessarily mean that it won’t work 
Thanks
Turris Shield is software- and hardwarewise a locked-in MOX variant. And MOX is not supported by OpenWrt.
BUT - Turris OS is a customized version of OpenWrt in that way, that there are software/ special functionalities added. Only view things are really different (the allmighty schnapps replaces the generation of configuration backups e.g.). I’d suggest to just use the benefits that TurrisOS is offering over OpenWrt (snapshots via ˋschnappsˋ), because all in all there is not really something missing. And you can decide which version of OpenWrt (on which in the end TurrisOS is based upon) to run (currently you can choose out of 19.07.8 (TOS v.5.x), 21.02.1 (TOS v.6.0) and OpenWrt snapshots (TOS v.7.0-future)).
So in my eyes there is nothing missing. If you really want to get rid of installed packages - have a look in this forum, there is information on how to do that.
You can even customize via doing custome builds.
edit: Suggestion from my point of view would be to either opt in for a MOX (enough for personal firewall, but don’t expect throughputs >500MB/s without traffic shaping) or Turris Omnia without wifi (small business solution, up to 500MB/s bidirectional throughput with traffic-shaping, up to 1GB/s without).
If this is not enough for you, you would want to opt in for X86-hardware and pfsense for example.
But it is almost completely supported in vanilla kernel. 
So, I hope that it will be supported in OpenWrt soon.
Thanks. My focus is OpenWRT as I need to get some experience with that and the package for CrowdSec (where I work). So for now I borrow an omnia from a friend and installs OpenWRT on it and maybe Turris later. Eventually I’ll probably by a Pi-derivative with at least two nics like the nanopi r4s for instance… We’ll see.