It’s something I often hear complaints about. Several of the Home Assistant users I know love the way it integrates all their smart devices together, but say they find making good dashboards difficult.
Improvements like proper drag and drop and better auto categorisation and population will go a long way to help them. The old default dashboard that just lumped everything in one screen isn’t a great way to get started.
It's a feature that's often been requested, but hasn't appeared yet. The best option out of the box is creating non-Administrator users and then creating custom dashboards and panes per user with only the controls they need.
But that doesn't stop a user from poking around still, because they can still access all devices and entities through features like the Logbook - which is always accessible because sidebar items can't be controller per user.
There are some HACS bits that might be able to lock things down a bit further, like Kiosk and Guest modes.
I've heard some people get round this by setting up inebriations with Apple/Google/Amazon ecosystem, only exposing the desired entities/devices, and then giving others access to those and keeping them out of Home Assistant altogether.
It's a feature set I wish they would add/expand, I'm sure anyone with a home office and mischievous children would agree.