I have just updated my newifi-D2 from 19.07.6 to snapshot. I have noticed that it is not possible to access the switch anymore, rather all the port seems to get its own network physical interfaces, lan1-4 and wan
There is also an eth0 which I do not know what is about
I'm not completely positive because there's not really a lot of communication about its progress, but I believe at this point there is still only a proposal for DSA support in LuCI. The Github issue isn't closed yet. Someone please CMIIW.
No, there isn't, and probably won't ever be. Under the DSA paradigm, switches are devices (specifically "bridge devices") which means that in LuCI they would go under "Interfaces" where they would be configured like other physical and not-so-physical devices.
Thing is, DSA is really flexible. And this flexibility can get very complicated very soon. Especially since our routers have in-SoC devices, switches, wireless devices, and all of them interoperate. If you sprinkle VLANs on top it becomes a veritable nightmare to create a web interface that makes sense and does not break things left and right if used only slightly wrong. So I can really understand the trouble of creating a LuCI interface, and I don't envy the devs one bit for the task. I imagine the reason why there is not a lot of communication about DSA in LuCI is that there's a frightening amount of hair pulling going on behind the scenes.