OP, I namechanged as this is somewhat outing.
My mum smashed her elbow as a child (she had several broken arms, collarbones, elbows over the years). Her elbow was pinned into place with wires, and she was never able to move the joint after that. It was set at an angle, not straight, so she could still use the arm (mostly, there were a few things she couldn't do). This was in the 1950s, so not as advanced as now.
But I recall she told me that some things she found helpful at the time included having things like cross body bags to carry stuff around the house, or a couple of rigid baskets to hand to carry things with your good arm, especially up and down stairs. Also if you have something in your good hand and want to carry it downstairs, rest your bum on the handrail or wall to provide a bit of extra support as you step down.
There may be some things from occupational health that the nurses can give you to assist the practical side.
While your DD might not understand you can't pick her up, maybe there are ways to distract her into something you can do together that won't interfere with your arm. Games on the floor, walks around, perhaps someone in your family will have some ideas.
My fingers are cross that the surgery goes well, and I can appreciate how hard it is right now not to be with your DC. Do they ahve a counsellor who can talk with you? You may need to talk about the accident too, which may be contributing to your MH worries right now.