Adam Block is an award winning astrophotographer from the USA who shares much of his skills via his website and recently, YouTube.
His latest series focusses on the Batch Processing tool within PixInsight but is an excellent resource for those willing to dive deep into post processing with PixInsight. There are 10 parts so far.
Alternatively, if you want an broader introduction to PixInsight check out the “Free Videos” section of his website for “Pixinsight Fundamentals” https://adamblockstudios.com/categories/Free_Content