This is just one approach using an LM555 output driver.
There are existing FET drivers that are better.There are existing CMOS FET drivers that are better. eg MIC4451 https://www.mouser.com/ds/2/268/mic4451-779120.pdf
Rce is the term I use to define Vol/Iol at 250 mA or (Vcc-Voh)/Ioh
with f(-3dB)=0.35/Tr and Tr=0.1us f-3dB> = 3.5MHz is not too hard with 100V/us slew rate and >250mA peak drive.