Got mines from Ebay. Here are 2 links I found them on. I purchased from 2nd link. Never installed mine since they only fit WT/Trail Boss model that come with key turn to start.
Hope it helps.
https://www.ebay.com/itm/Knee-Bolster-GM-84487351-Multi-Switch-GM-84688687-2019-Silverado-Sierra/264542468153?hash=item3d97f5b839:g:HpAAAOSwCB1d2EFz
https://www.ebay.com/itm/2019-Chevy-GM-Auxiliary-5-Button-Kit-Steering-Panel-Work-Trail-Boss/293239471062?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2748.l2649