Yes, I use pretty much all the VE mods and Sidearms recognizes sidearm eligibility based on their mass. You can see in Mod Config when you adjust the sliders the icons will show up to show what weapons meet the specified mass limitations.

I use Vanilla Framework Expanded and sidearms but weapons keep disappearing when equipped. Don't know if it is in conflict

However there is a bug related to shields if u have "Re-equip dropped weapons" enabled.
Every time u force a pawn to drop a shield it will remember it as sidearm, without showing one on ui and pick N+1 remembered shields. U can easily end up with a pawn hauling 10 shields around.
Only two ways I found to fix this are eaither disable "Re-equip dropped weapons" or fix <rememberedWeapons> block for a pawn in a save file :\