In this case, it seems that D-Link uses different names for the same realtek based hardware. Or at least for hardware that is similar enough that the existing OpenWRT images for one can be used on the other:
- openwrt-23.05.2-realtek-rtl838x-d-link_dgs-1210-20-squashfs-sysupgrade.bin does run on a D-Link DGS-1210-16 Rev. G2
- Checking the OpenWRT sources strongly suggests that openwrt-23.05.2-realtek-rtl838x-d-link_dgs-1210-16-squashfs-sysupgrade.bin should run on a realtek based D-Link DGS-1210-20 (which should be revision F if I can believe the D-Link website)
- Comparing the current english and german product pages for the DGS-1210 family suggest that the following devices are either identical or at least similar enough that they can run the same OpenWRT images:
- DGS-1210-20 Rev. Fn and DGS-1210-16 Rev. Gn
- DGS-1210-28 Rev. Fn and DGS-1210-24 Rev. Gn
- DGS-1210-52 Rev. Fn and DGS-1210-48 Rev. Gn
The common pattern in the naming scheme seems to be that the english version counts all ports (including the 4 RJ45/SFP combo ports) in the device name, while the german version only counts the pure RJ45 ports.