been stuck like this for a while, with no download information. If I cancel, is it safe?
Yes, it should be safe to cancel.
Be aware that the package you are installing builds chromium from source. It will take quite a long time to build depending on your hardware and config. Potentially several hours.
There appeared to be a problem building chromium-vaapi anyways, I just went with regular chromium for now. All running ok
I was just about to suggest that.
Chromium from source takes about 3 hours to build on my Ryzen3 2200G + 8 Gb of ram…