Been driving Uber for two + years now and there is no welcome kit.
Lyft's welcome kit comes in about 2 months. Take the trade dress card. The plastic envelope that sticks to the windshield (good for Uber and Lyft) and toss the rest away. (unless you have a thing about pink mustaches)
You may want to keep the cheap "phone holder" to use for a GPS, but it is useless as a phone holder for TNC use.