You can install whatever you want on Turris devices. And you get schematics and gerber files.

https://project.turris.cz/en/hardware-documentation.html

Vanilla OpenWRT runs Omnia (Marvell Armada). OpenWRT support for IPQ9574 is WIP. Omnia NG is IPQ9574.

https://openwrt.org/toh/turris/turris_omnia

Turris has its own OpenWRT warapper, but you can just wipe it and install the stock OpenWRT.