All the sites are telling me the Lenovo Tab4 10 Plus has a USB C port

That is an older device, so support for the usb ethernet adapter is uncertain
The Poco M3 and X5 should work with most adapters
Personally I'll still go for one with the ASIX chipsets

Charger...
Lenovo tab - any basic 5v2a charger
Poco M3 - any Qualcomm Quick Charge 3 compatible charger
Poco X5 - you will need to use original charger and original cable for 33W fast charging, no other options

Something from a reputable brand like Anker, Ugreen, Baseus will do
Don't get those super cheap rm5 4 port qc3 chargers, they are dangerous
You can use a faster charger (like QC3) on an older device, it'll just charge at the supported speeds
Note: for the X5 I've seen some cables from the Essager brand that claim Xiaomi fast charge compatability, I never tried em before but they seem to have the extra wire needed for Xiaomi fast charging
Still need to use the original Xiaomi charger brick