You can use .ogg files in Monogame, in fact, it’s recommended.
My deferred engine Deferred Engine Playground - download
has a compiled size of 510 mb (uncompressed textures and large models) and uses 50mb of RAM. I use all the models and textures in my scene.
weirdly enough it doesn’t go up with higher resolutions, but I guess it’s only VRAM usage that goes up then.
My Car RPG Bounty Road
Has 490mb of data (uncompressed) and uses 170mb of RAM. In both cases I load all models / textures / sounds up front.