I have Android on my phone and sending a page to it isn't as seamless as I'd expect, like it sometimes either takes a while or I have to go in my Firefox Sync settings and force a refresh to get the page.
That... I should have thought of that a long time ago.
FF is great but the "send to device" feature has not worked for me in years. I suspect it got confused when I migrated my Apple profile to a new phone.