Lego update their range every few months. If you know they like Lego and she does, I’d pick one and ask if they have it.

I’m sure any gift you out this much thought into will be perfect. From my kids point of view, they get excited about presents whether they end up playing with it or not. What I’ve found works for spenifn time together is zoom videos with books that you can read to them while they read too. So you both have a copy of the same book.

At 6 they will be learning to read, presumably, so you can also listen to them read to you. All of the Julia donaldson books are great. However, I’d still get a toy present. This is more a thought for developing a relationship while apart, seperate to the birthday. You can even just pick up a copy of their favourite book near you and then only one copy needed. I love overseas from my family and at that age they are not able to hold a conversation on zoom for long as their attention span is low. Having the book brings a focus.

I’ve had friends bake together over zoom and also build the Lego together over zoom, so if you have the time that would work also.

Kids don’t differentiate between expensive and smaller sets of Lego at that age. The bigger sets are normally more advanced, so I wouldn’t stress about the size or cost.

I recently had my kids friends for sleep over. We got some Lego that day as a reward for something else. It was about Aussie $30, so maybe 25 USA dollars, and was 3 Harry Potter characters. They each were entertained for about an hour making them. Then an hour playing and they could each bring one home. There were 3 characters to build. They got more fun out of that each and collectively than a 100 dollar set.