Comparison
Microsoft resources
Approvals: What is Approvals? - Microsoft Support
Power Automate: Microsoft Forms in Power Automate - Power Automate | Microsoft Learn
Decisions.com
Steve Weber: The tool is powerful!, However, the training necessary to learn the basics, might take a month to complete if you only have a few hours in a day. Because I neared a project deadline I had to abandon the tool (grabbed Django). Personally I think Decisions is neat but too tricky for none developers. Programmers will want to code. That said, still try and Microsoft tools as Lego/micro-service(s) to build solutions where applicable. Use popular programming frameworks and languages when you need something advanced.