Is it possible to filter parts using mouse.Hit.p?

This is quite simple! If you intend on "Local Part" as a part in the character instance, it's VERY easy.

For this, you will use RayCasting in a LocalScript, as well as a function to find if something is a character.

local hit = mouse.Hit.p
local ray = Ray.new(
    game.Players.LocalPlayer.Character.Torso.CFrame.p,
    (game.Players.LocalPlayer.Character.Torso.CFrame.p - hit).unit * 500
)

function FindIfPlayer(part)
    if part ~= nil then
        if game.Players:findFirstChild(part.Name) ~= nil then
            return part.Parent --Return the character as the ignore
        end
    end
    return nil
end

local partHit, Position = workspace:findPartOnRay(ray, FindIfPlayer(partHit))

local MouseHit = Position --Set a new variable of the mouse's hit that ignored characters

Using the above code, it will find parts hit and ignore characters.