Late to the thread but wanted to add one more consideration that bit me:
Platform-hosted SD services have their own terms:
If you're not running SD locally and instead using hosted services like Automatic1111 on cloud platforms, or services like Civitai's image generation, Leonardo AI, or NightCafe - they each have their own Terms of Service that may add restrictions beyond the base SD license.
I was using a cloud SD service and didn't realize their TOS required attribution for commercial use. Had to go back and update all my Etsy listings.
Running locally with the official Stability AI checkpoints is cleanest from a licensing perspective. You only have the CreativeML Open RAIL-M to worry about.
Also +1 to everything Marcus said about LoRAs. I got a DMCA takedown on Etsy for a print made with a "anime style" LoRA. Wasn't even a specific character, just the style, but the LoRA creator had used copyrighted screenshots as training data. Lesson learned - vet your LoRAs carefully or train your own.