By that logic, Kid Ultra is on the same level as Miko as a healer, because he can keep his team just in different ways. The way is what determines whether a support is a healer or a shielder or rescuer or buffer or whatever. Ambra is only half a healer - while her staff slam, ultimate, and generally aggressive playstyle can help keep a team back, only one part of her kit is dedicated to healing. She is meant to deal damage, then heal on the side. Here, let me compare to Alani:
Alani is a healer with a mix of CC and rescue.
Ambra is a 50% damage - 50% healer support that heals a bit and keeps the heat off her teammates (there’s a joke about her Heat somewhere in there).
Alani gets high burst healing from her passive.
Ambra gets high burst damage from her passive.
Alani can heal in three ways: Riptide or Geyser (but not both), her passive, and her ultimate (with an optional helix choice; however, the other options represent Alani’s other paths.)
Ambra can heal in one way: sunspots. She technically does have a helix that lets her heal through her beam staff, so you could use that too, even though that wouldn’t be as effective as a. healing sunspots option b. Alani’s helices that heal
I would continue, but I feel like you get what I’m saying.
In short, Ambra could not keep a team as healthy as Miko or Alani could. Miko has the most healing-related abilities and helices in the game – well-known fact – and Ambra only has one. If you compared Ambra’s healing to Miko’s healing in a match (on separate teams, no wound) with to equal players, I can almost guarantee Miko would come out on top.