connecting my laptop to iPhone HotSpot using Ethernet adapter
Just for grins and giggles, I thought I'd give this a try and I could not get it to work.

Hardware was an iPhone 8 running iOS 13.3, Apple Lightning to USB 3 camera adapter, power from a third party power brick, Apple USB to Ethernet adapter, with an Ethernet cable to an older MacBook with built-in Ethernet.  Cellular service is from AT&amp;T if that matters.

I was able to get a hotspot working fine with a Lightning to USB cable to the same laptop so I know the hotspot function works.  To set up the test I disabled WiFi and Bluetooth on the iPhone and MacBook to avoid either device from looking elsewhere for the internet.  I verified a live Ethernet connection between the two by pinging the iPhone from the laptop.

After verifying that the hotspot function didn't work I wanted to check that the Ethernet would do more than a ping.  I set up the laptop to share WiFi internet on Ethernet to the iPhone and the iPhone was able to load web pages, with airplane mode enabled to assure it didn't connect by other means.

When enabling the hotspot function on the iPhone it did report that it was sharing the internet by USB-only, Ethernet was not mentioned.  Checking the settings on the Ethernet port I saw no IP address configured when left as auto-configure.  Internet sharing still did not work when I tried manual configuration.

I don't know if anyone cares about this anymore as I am resurrecting a zombie thread.  I was looking on if others tried this and I found this thread.  My intention on doing this was to ditch my poorly performing cable internet and instead use an old iPhone 7 for internet, to avoid having to tether my iPhone 8 every time and wanting Ethernet so I can share it on multiple wired computers without having to dedicate a computer for routing the internet.  It looks like if I do go with cellular internet at home then I'll have to stick with WiFi and USB from the iPhone, and anything on a wire would have to be connected by USB to the iPhone directly or have a computer in the middle to route from the iPhone to Ethernet.

Unless I missed something important somewhere I guess I have my answer.  I just thought I'd share my experimental results since so far it looked like educated guessing, and some time has passed which may have changed the result.  So, thanks and I hope this helps.