I encountered this same issues/desire and did manage to achieve a satisfactory result for my work email by using the 'use HTML signature' option in the settings dialogue.

I have included my signature 'code' below that I used (personal details redacted) in case it is helpful.

One important point is that you will need to find a version of the image file hosted online that you want to use for your email. If your company uses Gmail for corporate email this is easy, as it will be (most likely) hosted somewhere on the public google 'drive' for your company, but if your company doesn't have a publicly accessible space on your server where the image is located you could always host it yourself somewhere and link to that file in your signature code.

It ends up looking like the image attached here.