ive recently been thinking of the Martini Henry posted earlier, and honestly im curious now what else could be added in terms of relatively early to first world war rifles
here were a few ive been thinking:

possibly a vetterli of some kind (maybe also carbine variant)

a carcano would be another probably more likely possiblity

a gewer 98 would easily run off of mosin anims

you could easily make different variants of the mosin, maybe could get assets from rs2: winter war devs

and lastly to me, if someone worked on a lee enfield, you would have the most possible customization options.

i dont want to ramble or make this too hard to discuss, but you can definitely get most of the assets for these off of verdun or tannenburg, if not other games or online, regardless thanks for your time and patience!