No definitely not mean! But I would probably lean into the theme a bit even if you don't want to actually play it for long.
Does she have some baby dolls to play with and accessories for them? As she may like to be the Mummy or teacher or doctor looking after the baby, and it means you can have a bit of a more detached role being nearby while she plays.
We do non-baby things like this
Blow up a balloon and try to keep it in the air as long as possible.
Play "the floor is lava" by putting cushions on the floor and she has to jump between them and not touch the floor.
Listen to music and make up a dance or play something like musical statues, or let's dance like elephants/ballerinas/mice etc
Play simple board games/card games. Have a look around charity shops or car boot sales. Haba or Orchard games are normally good for this age. Uno is also good and crucially a round is very short. She may also be able to do some simple jigsaws - they usually have an age suggestion on the box and again loads to buy second hand and just donate again when they get too easy. If you get the ones for age 4/5 she might be able to manage with help.
Duplo is good for this age if you can find any and once you've built something together she can play little stories with the characters - there will be a set including a family with a baby I'm sure.
Crafts are great and there is always some event coming up that you can get her to make a card or picture or whatever for.
Do you have old photos of your DD/DS you could bring out to look through together? My DC absolutely love looking at old photos and hearing all the family stories. Also photos of DGD when she was a baby. And if you have any of your DC's old toys, she might like to look through those.
Would definitely insist on getting out of the house for some time as well. It always helps pass the time. I don't ask DC if they want to go because inevitably they prefer to stay at home, but they normally enjoy themselves when out. To avoid getting sucked into role play at the park, try giving her challenges to do.
I had a book which I have passed on to someone else now but it was called "The Busy Book for Toddlers" and had loads of different easy ideas in it, the only two I can remember now are to freeze some small toys (e.g. animals) in ice cubes and then let them use tools or warm water or just throwing the cubes to the ground outside to get the toys out. That is a good summer game. And the other one was using masking tape on floors/carpets to make patterns like roads for cars to drive, or things like hopscotch. It should not mark floors and is easily removed when the game is over.