Fundamentally, V2019 has same core features as V2007. The most noticeable difference is the beloved ribbon introduced in 2010. Along the way to 2019, the object model was upgraded with new features, some bug fixes, some new bugs (but overall, nothing major). I've not experienced any significant performance issues requiring re-booting Visio.
So, wrt $29...if it's too good to be true, it probably is. I cannot address any Office365 related issues. But, fwiw, V2019 plays well with Office10.