For people wondering how to do this in your own lives, have two phones. Have a phone that you install work stuff on, including proprietary apps like WhatsApp. Just tell the people around you hey you can contact me on WhatsApp, but I only see it when I'm at my desk during business hours. I do use more privacy focused platforms on my personal device that you can reach me anytime, such a signal or simple x or matrix. And you'll find a lot of people are very flexible as long as you give them some reason, and you're not being unreasonable yourself.
I disagree. I absolutely love the fact that I can just turn it off after office hours and throw it in a corner during holidays and weekends. Sure, it's a bit cumbersome to take two phones with you, but it's also cumbersome to take the laptop and everything with you all the time. Just put it in the same bag and you're good. Good to note, my employer provides me with a phone, so I didn't need to buy a second one. It also means that if I switch jobs, I just return the phone and still have my personal device.
But if it doesn't work for you, by all means, don't do it. For me the good outweighs the bad.
There is an app on f-droid called "shelter" that gives you access to Android Work Profiles. This is a sandboxed area of your phone that makes it function like a second phone. You can install apps that are only accessible from within that sandbox. You can install a second, sandboxed copy of an app. You can shut down all your sandboxed apps simultaneously.
I have a bunch of bullshit, garbage apps I very rarely use installed in my sandboxed "work" profile (Facebook, restaurant apps, and some other assorted trash apps) so they won't harass me at random.
Shelter is great, and work profiles are an amazing tool to have.
My intention with having two phones, one always at your desk for work items, is to set coworkers expectations that your not available on corporate systems 24/7. If they want to reach you outside of business hours, they will need to use better platforms. This demonstrates your being reasonable and using Whatsapp (or whatever) to be on the main platforms, but you have a real motivation to use the better platforms (like signal, etc)