When trying to summon a boat, the only way to do it is using “/summon boat ~ ~ ~” which only summons an oak boat. There is no option or way to summon any other type of boat.
1. Go into the command screen.
2. Type /summon boat.
3. See there is no option to summon other boat types.
4. If boat is summoned it’s only oak.
To be able to summon boats the same way minecarts (“/summon chest_minecart ~ ~ ~”) by just describing which type of boat. ie; “/summon spruce_boat ~ ~ ~”.