I have a “853” type hot air tool from about 20 years ago. Nothing special, but it’s been working well for me over the years.
A few years ago, I built a preheater using a spare heater from a 3D printer, with some pyrogel insulation material that I had on hand to go underneath so that I can easily use it on my workbench.
I just use a bench supply and dial in about 35 watts of power.
I placed speed bugs (just bits of painters tape) on the front panel to set the airflow and temperature to my preferred default. Once I turn it on, I give myself enough time for the tool to heat up and stabilize before I go to work.
If you have a board that you’re worried about damaging, get some ChipQuik to bring the melt temperature way down. Just be sure to clean up fully afterwards.