Do you have any tips using KDE Connect with a local VPN (Wireguard)? It works great for me on the same network, but unfortunately fails to connect outside of my network despite one (or both) devices connected to my VPN
To sync from android to your PC, you'd need to manually do it by pressing the send clipboard button in the KDE Connect app on your android device. It's due to a limitation imposed by Google. However sync from Linux to android should work automatically. Is that not the case for you?
On Firefox I can easily send a tab to another one of my devices using a Firefox account to link them if something like that sounds acceptable to you. I imagine the same is possible with Chrome.
But between systems this matters none. You will use the same KDE Connect or whatever software of your choice, no matter what the windowing service on each system is.