I was thinking that an indoor tree in the greenroom would be nice to have, but I want to know which trees are indoors and bird safe. I would like it to be a pretty big tree, not something small like a bonsai tree (which, if I'm not mistaken, is toxic). The only thing I find on my searches are safe houseplants and safe tree branches for perches.

I have a schefflera which is a popular perching spot. Some sites list it as safe and others list it as toxic, but I've never had a problem and the birds do like to chew on it. In fact the cockatiels almost killed it when it was smaller. It contains oxalates which is why some sites say it's toxic.

Is it high maintenance?

It's pretty low maintenance. I water it about once a week. It keeps getting taller so once every couple of years I put a taller stake in the pot and tie the branches to it so it stands up straight instead of flopping over. It's about 8 feet tall now. The cockatiels don't hang out in that room as much as they used to so they aren't doing enough to keep it trimmed shorter lol. When they do hang out in it they like to clip off the leaves.

Any other safe indoor trees? The plant nursery around me doesn't have schefflera.

You could look at what they do have, then google any that you like the look of to see if they're safe.

I believe most fruit trees can be bought in smaller versions and are bird-safe.

Like apple or pear.

Those are higher in maintenance though and won't last long leave-wise once the cockatiels chew on it

Don't know if that will kill the tree though.