Anker USB C Hub with Ethernet, 8-in-1 Multiport Ethernet Adapter with 4K 60Hz HDMI Port, 85W Power Delivery, 10Gbps USB C and 2 A Data Ports, microSD SD Card Reader, for MacBook Pro/XPS/iPad and More

I have a SL4 as well. Its still going strong after 4 years. Dont buy the MS docks. Not necessary and WAY too expensive. Here's the link to what I use. It works on SL4 great and has everything needed. Anker USB C Hub with Ethernet,... https://www.amazon.com/dp/B087QZVQJX?ref=ppx_pop_mob_ap_share

If you're going to an Apple store, when you pick it up I'd consider asking them if they can walk you through the setup if you think you'll need it. I seem to recall they do a brief 'intro to the Mac' as well. Also, have you gotten a USB-C hub yet if you're planning to use legacy USB-A cables, HDMI monitor, or other such things? I opted for this one from Anker but there are less expensive brands and versions if you don't need all the features.