@goldenmindset I'm in the same boat and tbh, there's not much you can do to keep the attention of small children. Mine were 3 and 1 when I started facetiming (on android so Google Meet) them and their mom would only let me talk to them once per week while they were eating breakfast. I could barely keep their attention bc they were usually distracted by asking mom for more Cheerios or blueberries or whatever.
I try to ask them if they're having a good day, what they're eating and if it's good, then ask them what colors the food was or how many pieces they had they had. When that ran its course after a few minutes, I would grab some toys to play with so they could watch, then usually finish up with special effects filters - turning my head into a cat or strawberry, or put on a filter hat or something. I ask them to tell me what I am and what color, what sounds the special effects characters make, etc.
About 20 minutes was all I could get out of them before my oldest finished eating and wanted to go play with toys and he'd disappear.
I finally got split custody 50/50 and I try to let their mom FaceTime them when I have them. They're 4 and 2 now. I put them in a room and they play hide and seek with mom and show her their toys and she tries to ask them about their day and my oldest will say what he was doing just prior to the call. If I don't keep them company then the call would realistically last 5-10 minutes, but they usually need help with something or want me to play with them so the calls last about 30-45 minutes before she decides it's time to hang up.
I guess the point is it helps when the other parent facilitates the interaction. If not, learn about child development and where a 6 yr old should be and try to meet in the middle doing what you can for as long as you can.
It may seem pointless now, but the intention is what counts and the fact that you made an effort bc at least you can say you tried. If you give up, you can't say you tried. If you keep it up, even for a few minutes at a time, then you'll be glad you did. I think of it like saving your treasure 1 dime at a time. 1 dime feels worthless now, but add a dime each time and they'll add up and be worth the effort later.