It should be noted that hardware encoders are finite in availability -- this means that they are often not something you can rely on when in a group-video call with multiple peers requesting video streams. If using an Nvidia GPU, you might be limited to 2 or 3 hardware encoders, just like an iOS device, which doesn't work well if streaming to many viewers.
The VP9 codec offers higher quality than most default codecs, but it also uses higher CPU load. AV1 may be even worse, so sometimes H264 is best. Just something to be aware of.
Currently a web-browser does not allow a single video encoder to share video with multiple guests, at least not at low-latency. This is a limitation that will be addressed in the future, but it's a current limitation now.