Honestly, I was a little relieved that Doom Eternal did away with the classic Doom starter pistol. While its 2016 iteration was pretty useful, what with its infinite supply of ammo, going straight to the shotgun felt right, and besides, you don't need infinite ammo when you've got a chainsaw and an abundance of ammo-spewing imps.
But for those who still miss it, it turns out the weapon does actually exist in Doom Eternal's code. New Blood founder Dave Oshry posted footage of it on Twitter:
You've probably heard by now that DOOM Eternal originally had a pistol and YES it's still in the game and accessible via console commands (with Cheat Engine)I've heard it was scrapped because it didn't really fit the combat flow. Still pretty sweet looking. pic.twitter.com/FZFmrhQwCBMarch 26, 2020
Unfortunately, Doom Eternal doesn't provide out-of-the-box access to its command console like classic id Software games of yore, but there is a way to access it if you use a Cheat Engine table. I haven't used it myself, but that's how the pistol was accessed in the Twitter video above.
Meanwhile, this YouTube video courtesy of Postposterous spends a bit of time playing with the hacked command console, discovering wholesome cheats like 'gibalicious', which basically spontaneously explodes all visible enemies.