I am on Xubuntu though if that makes a difference. And I have not tried for a couple of weeks. There have been many package updates since I tried last.
On Ubuntu 20.04 (with Gnome), it just worked (with the exception of Chromium/CEF/Blink based applications like Chrome and Teams, which needed the aforementioned command line argument to scale them). I actually had to undo most of the scaling changes that came across with my restored home folder. The one other thing I had to change was the Terminal font as the default was a little too small to use comfortably on my laptop screen - I opted for Liberation Mono Regular, 12pt (px?) with 1.10x height.
As a former long-time XFCE proponent, I recommend you give Ubuntu + Gnome a try. It's the best it's been since the Gnome 2 days, and is no-where near as power hungry as it has been in recent years. The most power-hungry application I'm running is Evolution, where the webkit process that renders HTML email frequently gets out of control and burns 40% CPU until I restart it (I'd use Thunderbird but the Lightning plugin https://github.com/ExchangeCalendar/exchangecalendar to handle Exchange calendar stopped working with recent versions of Thunderbird some months ago).
[org/gnome/desktop/interface]
text-scaling-factor=1.5
But you're right about Snaps. I love the concept (easier distribution, fewer dependency issues especially if you're a few years into the lifecycle of an LTS release) but they're not, in my opinion, production-ready yet so it's frustrating to see them pushed by Ubuntu. The main issues we have are the slow startups compared to non-snap apps (which is felt more acutely on old hardware with spinning disks) and the fact that they don't work if /home lives on an NFS server. That rules out their use for many academic and enterprise deployments.