I got r2d, but i recently gave up and replaced it with r3pro, which has slightly worse wifi, but usb 3, and of course openwrt support, which makes it a no brainer for me, it was cool to have the hard drive hidden inside the case of the router, but i dont rly care about looks that much, and dealing with xiaomi software, even when it wasnt outdated, it was always a pain. theres also (or was) r3pro (r3d?) with sata and hdd in, like r2d, and i just found out, that theres working openwrt on it, not official though Support request for Xiaomi MiWifi HD R3D - #29 by remittor
I think, back in 2020 or 2019, ive been searching for an alternative to stock openwrt, and i found some chinese page, that had some kind of openwrt baked on that router, but it was too complicated for me to try it, especially with not so great google translate from chinese, and it was my only router back then, so i didnt want to brick it.
Theres also this site https://www.right.com.cn/forum/thread-307721-1-1.html which kinda says it has openwrt working for r2d, but on the screens u can see only r1d and r3d, and the installation info is hidden for some reason...
I also found this https://blog.csdn.net/sunny_tan123/article/details/122255902 but its all very confusing, and i dont think im gonna try it, if it was in english, then maybe...