I didn't realise you could select other tanks. I would probably recommend consulting an artist regarding the art (you don't have to hire one, just join a discord server and ask for some help).
As for the sfx, chatgpt gave this code for godot:
var audio_player = AudioStreamPlayer.new()
audio_player.stream = preload("res://your_sound.ogg")
audio_player.bus = "Master" # Set the correct audio bus if needed
add_child(audio_player)
audio_player.play()
audio_player.connect("finished", audio_player.queue_free) # Auto cleanup
This should play the audio and not have it cut off (and remove the node upon completion). You could just create a function for this within the audio manager that takes the bus and audio location as parameters.