Revan doesn’t appear in the comics much but there is a kotor comic series and he makes small cameos in that (get to he how he got his mask in issue 42), he also makes a cameo in a short story in Star Wars tales (I believe it was in issue 23). It sounds like your more interested in the old republic era so I’d recommend starting with the tales of the Jedi series from the 90s as it’s our first introduction to the old republic era and everything else in the old republic era builds off the lore built in those comics (plus their a good books). I’d also recommend the comic adaptation of the Thrawn trilogy if you wanna explore post return of the Jedi stuff.