Fritzing supports “SVG Tiny”, plus some extras. I am not clear on the extras, but I found this reference which starts out with
According to Adobe Illustrator Help – Saving artwork: Save in SVG format, SVG Tiny does not support gradients, transparency, clipping, masks, symbols, patterns, underline text, strike through text, vertical text, or SVG filter effects.
I have seen transparency (opacity) in svg files used for Fritzing parts, but have never checked closely to see what actually happens on screen. Memory says that the opacity settings did get through to a fritzing exported svg image though. So you could try specifying a gradient, using the part, exporting the view to svg, then finally viewing the image using a program that DOES support gradients. Depending on your needs, that might be usable, if that export can be the view that people actually see.