I imported a PNG file into SketchUp (Free web version) and was hoping I could simply extrude it. Found out via SketchUp forums that PNG is NOT a format that SketchUp can interact with, let along extrude. The forums mention an out-of-date link to a tracer extension:
https://sites.google.com/site/spirixcode/code/spirix_bmp_tracer.rbz (broken link)
I found the updated link on Google Drive: https://drive.google.com/file/d/1tY2X41dqTl4ppTK2825n5YzCG_zJXmS8/view (just click the Download icon in the upper-right corner)
Note: I’m on the free web version of SketchUp and I don’t think I’m able to install this extension.