Is it possible to get Extra Attack or equivalent without taking at least 5 levels in a class?

I am planning a Forge Domain Cleric character and think Extra Attack would suit them, but it seems as though multiclassing is the only way that would be possible, given that Forge Domain Clerics don’t otherwise have Extra Attack.

However, I also want to the Saint of Forge and Fire feature at level 17 (assuming I survive that long) and do not want to sink more than 3 levels into a different class if I can help it.

The only ways I know of to get Extra Attack or an equivalent feature/ability are:

  • Sinking 5 levels into a martial class such as Barbarian, Fighter, Monk, Paladin or Ranger;
  • Sinking 6 levels into a class that gets Extra Attack via archetype feature, such as College of Valor Bard, College of Blades Bard, Bladesinger Wizard, etc;
  • Sinking 5 levels into Warlock and picking Pact of the Blade and the Thirsting Blade eldritch invocation;
  • Being a War Domain Cleric, who can make an extra attack via their War Priest feature at level 1, although this isn’t an “always on” feature like the others, and I am already intent on taking the Forge Domain, so this isn’t an option for me;
  • Finding a way to cast haste, but that isn’t an “always on” feature either and would likely require me to sink 5 levels into another spellcasting class since it’s a 3rd level spell that isn’t on the Cleric spell list;

Are there any other ways I’m missing, ideally that don’t involve sinking more than 3 levels into another class? I would prefer “always on” methods, even if it requires using my bonus action (a la the War Priest feature mentioned above, although two-weapon fighting is not an option because I plan on going Warhammer and Shield), and I’ll accept magic items, if there are any that let you have extra attacks.