Doom eternal and bf5 not support keyboard and mouse why?

The decision to support mouse and keyboard on console is down to each developer. You want to ask them about it. They may decide to add it at a later date.

A xim apex is handy

Using that device and other like it, to force mouse and keyboard for games that don't support mouse and keyboard will likely get you banned as it's classed as cheating,

I guess you could get away with it, if only playing single player campaign's but the moment you use these device's in online multiplayer, that when and where you'll risk being banned from the game or even Xbox.

The BF5 doesnt have support to mouse and keyboard in console. So is logic that they wont work.

Currently the games that supports mouse and keyboard are these:

Bomber Crew

Deep Rock Galactic (Xbox Dynamic Lighting)

Fortnite

Metro Exodus

Minecraft

Paladins

Sea of Thieves

Sniper Elite V2 Remastered

Strange Brigade (Xbox Dynamic Lighting)

Surviving Mars

The Sims 4

They Are Billions

Vermintide 2 (Xbox Dynamic Lighting)

Warframe

War Thunder

X-Morph Defense (Xbox Dynamic Lighting)

Pfff, people complaining about others using a mouse and keyboard probablys suck at the game they're playing and just want to shift the blame to those using a keyboard and mouse.

Personally, i enjoy PC shooters like Z-doom where i use a mouse and keyboard, it's pretty fun, but $150/£75 for a keyboard and mouse? I'd rather not.

Well seeing that mouse and keyboard is typically considered cheating when used on console it's not exactly just available on every game really so mouse and keyboard is usually done using a 3rd party device but it is not recommended as it could result in
suspension in some games if caught