Starting solids

My baby also isn't sitting up independently (6 months) but I didn't wait. I bought an "upseat" and have been feeding her in that until she can sit in the high chair.

I used towels to hold her up as per the HV Advice

If your baby can sit with a little bit assistance is ok. Other signs of readiness to starting solids: reach out hands grab things and put in mouth, shows interest in food

We absolutely waited. Waiting until your baby can sit unassisted before starting solids is recommended because it indicates that your baby has developed the necessary motor skills to safely eat solid foods. Sitting unassisted shows that your baby has good head and neck control, which is important for swallowing and reducing the risk of choking. https://feedinglittles.com/blogs/blog/starting-solids-the-importance-of-sitting-unassisted

My doctor said as long as my kiddo can sit up assisted or independently he can start solids if he was showing signs of wanting to eat solids. My kiddo does not sit independently yet. He is either in a seat or held by myself or someone else when I feed him. We are in the purée phase and he loves it and has not had any issues so far.