realtime dynamic reflections, which way to go? I'm working on my own engine and I'm struggling to find any techniques that give okay-ish reflections in realtime on dynamic scene.
So far the only technique I found that work in real time on dynamic scene is SSR but it's really heavy and have a lot of bias.

The idea of having multiple cubemaps and updating them in real time crossed my mind but because that mean re-rasterising the scene that also mean that every cubemap updated in realtime is a shadow casting that I can't do.

So my question is: is there another technique other than reflection probe (cubemap) or Screen Space Reflections ?

The artstyle of the game where the engine will be used is based on a lot of "almost mirror" reflections and it's not PBR.

[Edit]
To be a bit more precise with what I'm searching:


I do not need more than one bounce.
I do not want any baking that cannot be done at "loading time".
I prefer if the technique work with a per-pixel normal but if you
know a technique that work with a per-vertex normal I am also open.
I am open to techniques that only work in specific cases (like tiny
scene, deferred rendering only etc...) as long as it meet other
requirements.
If your technique is a feature of a global illumination technique I am
also open but I would prefer if it work stand alone.
If it can easily support GGX it's better but not required.
Inaccuracy is not a problem as long as it is predictable by the
artist
If there is only a single flat mirrored surface the solution is to render the scene twices, once normally. Afterwards you use stencil to mark the area where the mirror is visible.

Then only drawing into that area you render the scene again but mirror it around the mirror's plane and cull any geometry on the other side of the mirror.