Special embroidery digitizing software like the Janome Digitalizer can create a vector based embroidery design from a bitmap source, or even fonts (such as TTF TrueType fonts) in some cases. So it should be possible to use such programs in order to convert fonts (usually use them to make some kind signs) and prepare an embroidery designs in one of the vendor specific format, such as PES format in Brother machines.
Convert TrueType font file to Brother Embroidery file format.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert ttf to pes on Windows
An embroidery design tool from Janome
Convert from ttf file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.