I and Blake Harry made a mod which adds items from the WWII period.
For now this mod isn't big but we decided to publish it anyway.
This mod includes:

• Walther P39
• Kar 98K
• Stielhandgranate
• 6 posters
• Mustard gas grenade
• Mustard Agent Burns (New affliction caused by the mustard gas grenade)
• 9×19mm Parrabelum round (For the Walther P38)
• 7.92×57mm Mauser round (For the Kar 98K)
• Gas mask
• British mk1 helmet with cloth cover
• Trench Knife
• Russian MPL-50
• Jarmann Harpoon Rifle
• Radio
• Ammo pouch

Download link: https://github.com/Xizebo/WWIIMod/relea ... -Alpha-FIX
Please report any bugs here: https://discord.gg/eQ3CwmR

this seems promising

I released alpha 0.4 which includes:
- Mustard gas grenade
- Mustard agent burns (New affliction caused by the mustard gas grenade)
- Polish propaganda poster
- German propaganda poster
- Soviet propaganda poster
- USA propaganda poster
- A modified version of the Typhon, which includes most of the mods items.
Also the mod has been fully modified to work on barotrauma dev, and might no longer work on normal barotrauma!

Alpha 0.5 has been released! It includes:
-British mk1 helmet with cloth cover
-Gas mask
-Trench Knife
-Russian MPL-50
-Jarmann Harpoon Rifle
-British propaganda poster
-Canadian propaganda poster
-Radio
-Ammo pouch

Sadly the last release was broken, the new link should be fixed