from pydantic import BaseModel
from abc import ABC, abstractmethod

class ABC_1(BaseModel, ABC):
    @abstractmethod
    def do_something(self):
        pass

class ABC_2(BaseModel, ABC):
    @abstractmethod
    def do_something_else(self):
        pass

class A1(ABC_1):
    def do_something(self):
        print("Doing something in A1")

class A2(ABC_2):
    def do_something_else(self):
        print("Doing something else in A2")

class X(BaseModel):
    x: ABC_1 | ABC_2

a1 = A1()
a2 = A2()

x1 = X(x=a1)
x2 = X(x=a2)