I work from home and I have frequently considered whether it would be better for me to separate my personal Internet access from my work Internet access during the work day.
While I could, I don't want to have two computers & keyboards on my desk, I really want to toggle between work and personal using the same keyboard and mouse. Back in the day I would do that using a keyboard-video-mouse (KVM) switch. I've decided to try and see whether using VNC Viewer on my work PC to connect to the Raspberry Pi 4 running VNC Server is a workable solution.
It's real easy to set up VNC Server to run on the Raspberry Pi 4. If you are in the Raspbian desktop click Preferences, Raspberry Pi Configuration. Next click Interfaces, click Enable next to VNC and click OK. You may need to reboot but after a reboot you should see a VNC icon on the right of the top task bar.
You can also enable VNC Server from the terminal by running sudo raspi-config, select Interfacing Options, VNC and Enable.
You need a VNC Viewer 
app on your PC, which I had already installed. Click File, New Connection, enter the IP address for the Raspberry Pi and enter a friendly name. Click OK.
>You can find VNC Viewer apps for just about every platform, including iOS and Android, which make this configuration accessible for must about any device that I own.
A new icon with the friendly name you provided should appear within the VNC Viewer window. All you need to do at this point is double click that icon to connect to the computer.
I've found that using VNC to access the Raspbian desktop on the Raspberry Pi 4 and running Chromium is workable. When I type I don't see any lag in display of characters or cursor movement. Web pages display fast enough, with some slight flicker as I scroll up/down pages. I can run Gmail with no problem, and I can enter content on this wiki.
Audio playback does not occur within VNC, to hear audio I connect headphones into the 3.5mm audio port on the Raspberry Pi. I have found that you cannot play music in Spotify in Chromium on the Raspberry Pi, apparently for some DRM reasons. I did find raspotify that makes the Pi a Spotify connect device, which means that I can control music playback but I don't think that is very practical. I can play music I have stored on Google Play Music.
Video playback works within VNC but not very smooth, so I wouldn't recommend paying it remotely in this manner. I do note that YouTube playback is good directly on the Raspberry Pi, but not as good as on a regular PC.
I don't often stream video or music from a PC and if I want to play music I can use my phone, iPad, or Google Home. Mostly, I just read web sites and check email and for that VNC access to the Raspberry Pi 4 works very well.
I've found a series of blog posts at LinuxLinks about using the Raspberry Pi 4 as a desktop computer. site One particular post that I found useful is the one about web browsing . I've tried the smooth scrolling setting change in Chromium and found it does speed up redraw when scrolling a page up/down. I am also trying the Vivaldi browser, which does seem to be a tick better but I am not sure it is significantly better to cause me to switch from Chromium.