I believe if it's acceptable in the office, it's acceptable at home, and things you wouldn't do in the office should not be done at home in an online meeting.
You should be sat facing the camera listening to whoever is speaking. Maybe you take a sip of water/coffee, write down some notes or whatever, but you shouldn't be doing anything else.
Certain things like your background, family walking by, kids making an appearance can't always be helped but should be avoided if possible to prevent the meeting being interrupted.
Smoking, eating, shaving, flossing, painting nails, online shopping etc... No. these aren't really acceptable in my opinion. That is just common sense. You can wait to do these after the meeting.
Things like this give the impression you aren't listening, and eating or smoking can be off-putting. It depends on company culture, but most people will consider these things a little rude.
In all meetings I've been in, these things haven't really come up. Just use your best judgement.