Yes, it should work. At some point in the distant past, I've done just that.
WRT NetSurf's behaviour, RUfl attempts to open Homerton.Medium\\EUTF8. If that succeeds, it assumes there's a UCS font manager installed. The only Font Manager version checking that happens is to determine whether background blending is supported. The OS version doesn't come into it.
The screenshot on the RUfl website is of rufl_chars, which simply uses RUfl to attempt to display glyphs for all codepoints. There's nothing more to it than that.