class Autocompleters(commands.Cog):
    def __init__(self, bot) -> None:
        self.bot: commands.Bot = bot

    async def category(self, inter: disnake.CommandInteraction, query: str):
        print(type(self))  # <<<<<

        categories = ["things", "more", "stuff"]
        return [c for c in categories if query.lower() in c]


class Misc(commands.Cog):
    def __init__(self, bot) -> None:
        self.bot: commands.Bot = bot

    @commands.slash_command()
    async def test(
        self,
        inter: disnake.GuildCommandInteraction,
        cat: str = commands.Param(autocomplete=Autocompleters.category),
    ) -> None:
        await inter.send(cat)

async def some_autocompleter(
    self: commands.Cog,  # Or a protocol
    inter: disnake.CommandInteraction,
    data: str,
):
    # if need be can isinstance(self, ...) with a cog class or a protocol
    return ...

class Misc(commands.Cog):
    @commands.slash_command()
    async def test(
        self,
        inter: disnake.GuildCommandInteraction,
        cat: str = commands.Param(autocomplete=some_autocompleter),
    ) -> None:
        await inter.send(cat)