I'm looking for a monospace font which has a lot of the unicode glyphs. In particular I'm interested in the speaker symbols, code points 1F507 to 1F50A.
I'm not sure if the speaker would be included, but have you tried GNU Unifont? It is monospaced, it comes in
You can see the insanely huge list of covered glyphs here.
Monospace, on the other hand, is based on Georgia and covers 2,862 glyphs. Apart from the languages, it includes:
You can use FileInfo to check which fonts support character U+1F507 or other characters. Maybe you will find the font you're looking for.
I found this one which looks great and has many glyphs though the ones you're interested in are not included : Everson Mono on FileFormat or the original web page. I have counted 8835 glyphs but FileFormat mentions 9756 of them.
Please note that this is a shareware: