Powering battery powered tools from the power grid
No reasonably-sized and priced 20V PSU will be able to deliver the power that your 20V tools need.   You are trying to design a corded tool that can last through a big job.  The correct solution is to buy actual corded tools.  Just the ones that you actually need for such big jobs.   Plan B would be to buy more, bigger, batteries and a multi-battery charger that you can keep near your work location.
I don't know what current is drawn by battery-operated tools but we can guesstimate. A typical corded 120V saber saw or rotary saw is rated at 10 or 12 amps, therefore consumes say 1400 Watts.  At 20V that means a tool with similar power needs to draw 70 amps from the battery.    You could improve this guess by rigging up one of your tools to actually measure the current from the battery but let's start with this.  You are looking for a 20V 70A PSU.
Forget about laptop PSUs .... even the biggest ones the size of bricks meant for whacko-crazy gaming laptops only provide a small percentage of that power.  A typical laptop PSU is 65W.  Big ones are over 100W but nowhere near 1400.
20V 70A PSUs do exist, but they are very expensive, well over $500 and they are enormous and typically designed for permanent installation in a workshop.  They are specialty items.  You won't find one that is practical or economical for your intended use and it certainly would not be more convenient than charging and swapping batteries.
One last thing: If you did manage to rig something up that could deliver the kind of power you want to your tool, you would probably electrocute yourself.  Unless you designed it with the same safety standards as an AC-powered tool.  Double insulated cables, sockets, and plugs, fuses, etc etc ... all the things designed to protect you with dangerous power delivery.  Are you going to design and build that into your 20V solution?  No.  So you'll eventually get killed.   Just go buy one or two corded tools!