Not sure if it counts, but gnome-font-viewer might fit the bill.

You can probably run something like gnome-font-viewer /usr/share/fonts/open-sans/OpenSans-Regular.ttf and it should show you the font, although I haven't verified that myself.

Here are it's dependencies:

$ dnf repoquery --requires gnome-font-viewer
Updating and loading repositories:
Repositories loaded.
libadwaita-1.so.0()(64bit)
libadwaita-1.so.0(LIBADWAITA_1_0)(64bit)
libc.so.6(GLIBC_2.38)(64bit)
libcairo.so.2()(64bit)
libfontconfig.so.1()(64bit)
libfreetype.so.6()(64bit)
libfribidi.so.0()(64bit)
libgcc_s.so.1()(64bit)
libgcc_s.so.1(GCC_3.0)(64bit)
libgcc_s.so.1(GCC_3.3.1)(64bit)
libgio-2.0.so.0()(64bit)
libglib-2.0.so.0()(64bit)
libgobject-2.0.so.0()(64bit)
libgraphene-1.0.so.0()(64bit)
libgtk-4.so.1()(64bit)
libharfbuzz.so.0()(64bit)
libm.so.6()(64bit)
libm.so.6(GLIBC_2.2.5)(64bit)
libpango-1.0.so.0()(64bit)
libpangocairo-1.0.so.0()(64bit)
rtld(GNU_HASH)

It does also let you view fonts installed on your system, but I don't see why that should be a deal-breaker.

There is also the display command, provided by ImageMagick. My understanding is that it only supports X11, but it should work just fine under XWayland.

It isn't a dedicated font viewer, but I've used ImageMagick's display utility to preview fonts.

These types of apps became fairly irrelevant with the advent of Web Fonts and sites that already do all of this.

There's Fontbase, Gnome's Font Manager, KDE's Font Viewer and FontForge that are still maintained.

The fact that you're asking for whatever tool to not use something like QT or GTK is asking for the moon here. These types of applications you describe are generally packaged with a DE for this very use. I don't think there's a real use-case for someone to develop this independent of any DE, honestly. That's what they're most useful for.

Super modern bash script.

fontviewer.sh > /tmp/viewfont.html && xdg-open /tmp/viewfont.html

Pastebin script in here

What features do you need? Just render a string with a given font and that’s it? Or something more advanced?

Have you looked at the Arch Wiki already?

It's not you, the web has forgotten how to be searched.