Kind of interesting how quickly the smartphone usage exploded but also how it wasn't that long ago. Early Z most definitely grew up as PC users while late Z grew up with mobile being the primary website visiting tool.
I had to do some quick checking and this is what I found.

If we use Wikipedias timeline picture then Zoomers are born 1997-2012 (the text also references 1995, but I used the graphic):

https://en.wikipedia.org/wiki/Generation_Z

In 2011 (Gen Z are now -1 to 14 years old) web traffic was predominantly according to smartinsights.com:

I think that here the main point to remember is that many users will continue to access the web via their desktop PCs. In 2011 most companies I talk to still have a tiny proportion of their web traffic via mobile searches - it's usually much less than 5% - so it's worth checking your analytics for mobile usage first and foremost.
https://www.smartinsights.com/mobile-marketing/mobile-marketing-analytics/mobile-usage-statistics-2010-2015/

In 2015 (Gen Z are now 3 to 18 years old) things has begun to switch with most western countries reporting between 15% to 30% of web traffic being mobile:

https://datareportal.com/reports/digital-2015-global-digital-overview

In 2020 (Gen Z are now 8 to 23 years old) 61% of US website visits are from mobile devices:

Mobile devices drove 61% of visits to U.S. websites in 2020, up from 57% in 2019. Desktops were responsible for 35.7% of all visits in 2020, and tablets drove the remaining 3.3% of visitors.
https://www.perficient.com/insights/research-hub/mobile-vs-desktop-usage