These are called ladder jacks. They are available at most hardware stores that sell ladders here. In my region you’re still allowed to use them if you set up guardrails or are tied off. I was working on my own house in this video so there are no governing safety regulations for working in your own home. They are definitely VERY handy for small jobs like this where setting up pump jacks aren’t really worth it and where you can’t access the location via a man lift. With anything, there are risks -

7.4K views · 49 reactions | Our Louisville Ladder Pump Jack takes you from the ground to the top in one system. Compatible with recommended scaffold, plank, and nestable stages, this pump jack system allows you to work safely while on the job and meets or exceeds OSHA and ANSI standards. https://louisvilleladder.com/locationfinder/main/finder | Louisville Ladder | Facebook