This isn't an exhaustive list of blogs out there, just some that I use frequently, or as I come across them. If you have a blog you'd like to see here, ping me at email@example.com. Check the SNDev HUB for a more up to date list.
SNDevs HUB - This is a collection of various resources as well, and can be updated on Gitlab
The amount of ServiceNow courses on Udemy has exploded, but these are the ones that helped me as a junior administrator and developer, keep an eye out for sales to get courses cheaper.
This is a great free course put out by Travis Toulson from Code Creative