I have not found a forum thread for these yet, though I know there are a few users and developers around. So I decided to create one 
Let's start with installation instructions since I have not found anything public.
- The gateway (8733 in my case) comes with a smartRG image, which I did not care for. A serial connection is easily available, and the gateway uses u-boot.
- Download smartrg_sdg-8733-initramfs-kernel.bin file to a laptop, rename it as openwrt.430, set up the laptop with a 192.168.1.10 static address, start tftpd on the laptop, and connect the laptop's ethernet port to one of the gateway's lan ports
- Boot the gateway. During boot, "autoboot in 2 seconds" is shown on the serial; pressing 's' and 't' during these two seconds brings up an u-boot command line.
- Type
setenv boot_mode openwrtand thensaveenvso that u-boot will boot openwrt (instead of its default smartRG image) in the future. The default image comes with mmcblk0p4 and mmcblk0p5 partitions that are intended to hold an openwrt kernel and rootfs respectively, and u-boot environment has a boot_mode for booting from these partitions, but the partities are empty (zeroed) in the initial image, so we have to supply our own openwrt image. - Type
run boot5to download and boot the openwrt image. It will take an address of 192.168.1.1 as is usual for new openwrt installations. - From there on, scp smartrg_sdg-8733-squashfs-sysupgrade.bin into the gateway, and then ssh there and run
sysupgrade -n -v. The gateway will now reboot into the newly installed image.
the 24.10.0 images work pretty well as far as I could see, however, I was not able to get an AP running in the 6GHz band. iw phy lists these frequencies (I configured the radio for the US region):
* 5955.0 MHz [1] (12.0 dBm) (no IR)
* 5975.0 MHz [5] (12.0 dBm) (no IR)
* 5995.0 MHz [9] (12.0 dBm) (no IR)
* 6015.0 MHz [13] (12.0 dBm) (no IR)
* 6035.0 MHz [17] (12.0 dBm) (no IR)
* 6055.0 MHz [21] (12.0 dBm) (no IR)
* 6075.0 MHz [25] (12.0 dBm) (no IR)
* 6095.0 MHz [29] (12.0 dBm) (no IR)
* 6115.0 MHz [33] (12.0 dBm) (no IR)
* 6135.0 MHz [37] (12.0 dBm) (no IR)
* 6155.0 MHz [41] (12.0 dBm) (no IR)
* 6175.0 MHz [45] (12.0 dBm) (no IR)
* 6195.0 MHz [49] (12.0 dBm) (no IR)
* 6215.0 MHz [53] (12.0 dBm) (no IR)
* 6235.0 MHz [57] (12.0 dBm) (no IR)
* 6255.0 MHz [61] (12.0 dBm) (no IR)
* 6275.0 MHz [65] (12.0 dBm) (no IR)
* 6295.0 MHz [69] (12.0 dBm) (no IR)
* 6315.0 MHz [73] (12.0 dBm) (no IR)
* 6335.0 MHz [77] (12.0 dBm) (no IR)
* 6355.0 MHz [81] (12.0 dBm) (no IR)
* 6375.0 MHz [85] (12.0 dBm) (no IR)
* 6395.0 MHz [89] (12.0 dBm) (no IR)
* 6415.0 MHz [93] (12.0 dBm) (no IR)
* 6435.0 MHz [97] (12.0 dBm) (no IR)
* 6455.0 MHz [101] (12.0 dBm) (no IR)
* 6475.0 MHz [105] (12.0 dBm) (no IR)
* 6495.0 MHz [109] (12.0 dBm) (no IR)
* 6515.0 MHz [113] (12.0 dBm) (no IR)
* 6535.0 MHz [117] (12.0 dBm) (no IR)
* 6555.0 MHz [121] (12.0 dBm) (no IR)
* 6575.0 MHz [125] (12.0 dBm) (no IR)
* 6595.0 MHz [129] (12.0 dBm) (no IR)
* 6615.0 MHz [133] (12.0 dBm) (no IR)
* 6635.0 MHz [137] (12.0 dBm) (no IR)
* 6655.0 MHz [141] (12.0 dBm) (no IR)
* 6675.0 MHz [145] (12.0 dBm) (no IR)
* 6695.0 MHz [149] (12.0 dBm) (no IR)
* 6715.0 MHz [153] (12.0 dBm) (no IR)
* 6735.0 MHz [157] (12.0 dBm) (no IR)
* 6755.0 MHz [161] (12.0 dBm) (no IR)
* 6775.0 MHz [165] (12.0 dBm) (no IR)
* 6795.0 MHz [169] (12.0 dBm) (no IR)
* 6815.0 MHz [173] (12.0 dBm) (no IR)
* 6835.0 MHz [177] (12.0 dBm) (no IR)
* 6855.0 MHz [181] (12.0 dBm) (no IR)
* 6875.0 MHz [185] (12.0 dBm) (no IR)
* 6895.0 MHz [189] (12.0 dBm) (no IR)
* 6915.0 MHz [193] (12.0 dBm) (no IR)
* 6935.0 MHz [197] (12.0 dBm) (no IR)
* 6955.0 MHz [201] (12.0 dBm) (no IR)
* 6975.0 MHz [205] (12.0 dBm) (no IR)
* 6995.0 MHz [209] (12.0 dBm) (no IR)
* 7015.0 MHz [213] (12.0 dBm) (no IR)
* 7035.0 MHz [217] (12.0 dBm) (no IR)
* 7055.0 MHz [221] (12.0 dBm) (no IR)
* 7075.0 MHz [225] (12.0 dBm) (no IR)
* 7095.0 MHz [229] (12.0 dBm) (no IR)
* 7115.0 MHz [233] (12.0 dBm) (no IR)
iw dev shows:
Interface phy0.2-ap0
ifindex 13
wdev 0x5
addr 38:f8:f6:83:c0:84
type AP
txpower 6.00 dBm
multicast TXQ:
qsz-byt qsz-pkt flows drops marks overlmt hashcol tx-bytes tx-packets
0 0 0 0 0 0 0 0 0
Radios: 2
Interface phy0.1-ap0
ifindex 12
wdev 0x4
addr 38:f8:f6:83:c0:74
ssid buzz
type AP
channel 153 (5765 MHz), width: 80 MHz, center1: 5775 MHz
txpower 25.00 dBm
multicast TXQ:
qsz-byt qsz-pkt flows drops marks overlmt hashcol tx-bytes tx-packets
0 0 0 0 0 0 0 0 0
Radios: 1
Interface phy0.0-ap0
ifindex 9
wdev 0x1
addr 38:f8:f6:83:c0:64
ssid buz
type AP
channel 1 (2412 MHz), width: 20 MHz, center1: 2412 MHz
txpower 26.00 dBm
multicast TXQ:
qsz-byt qsz-pkt flows drops marks overlmt hashcol tx-bytes tx-packets
0 0 0 0 0 0 0 0 0
Radios: 0
I am not sure why the 6GHz radio (phy0.2) doesn't seem to be running (only showing a txpower of 6dBm, and no channel despite having one configured in /etc/config/wireless).