My girl is tall and now just over 8 months old. She can mostly sit unsupported, a little wobbly still though! She gets on all 4s to crawl and rocks but not crawling yet
Both my girls have been quite tall for their age, this one has been sitting since around 6 months and is on the verge of crawling but my eldest didn’t start crawling until she was 10 months. I’m not sure height has anything to do with it, they all just develop at their own pace. My first was an early talker and is very advanced with her language skills but isn’t as fast as other children her age. I think they just all have their own interests and personalities and will do what they want when they want 😄
7.5 months also and 78cm but also 24lbs. 😬😬. Started sitting unsupported but only the last 2 weeks. Very strong on his arms and loves tummy time but not crawling. However, crawling is between 7-12 months so I’m not concerned x
I have a long baby also! She was exceptionally tall until around 6/7 months and her recent growth spurt has made her even out a bit more, she still has ridiculously long legs though. Shes been sitting independently since 5/6 months and has been trying to crawl now! However one of my close friends has a baby who’s almost 9 months who was a similar length to your LG who has only JUST started showing interest in crawling and just about sit on her own! The sitting independent milestone can be 4-6 months for early developers, or up to 8/9 months! Some babies also hair straight up skip crawling and go to stand around 9 or so months too! If your baby is happy and hitting other milestones I wouldn’t panic TOO much. But if you’re ever concerned your red book should have health visitor details within it to contact!