The Windows emoji keyboard (Win+. or Win+; whichever is more comfortable for you) has a lot of the Unicode math symbols under its Symbols tab (marked with an om

The Windows emoji keyboard (Win+. or Win+; whichever is more comfortable for you) has a lot of the Unicode math symbols under its Symbols tab (marked with an omega). It has a pretty good IME-ish type to search experience for regular emoji, but doesn't support type to search under the Symbols tab. (I wish it did and hope it is something they consider adding.)