Sander sealer under catalyzed polyurethane?



I have a flamed maple/alder body coming soon which I plan to finish using stain and clear coat.

The product I planned using in order:
[list type=decimal]
[*]Colortone powdered grain filler
[*]ColorTone Liquid Stain
[*]Sander sealer?
[*]Nason® SelectClear™ 498-00™ 2K Urethane Multi-Panel Clear

I have used 2k Polyurethane directly over water-based dye before without issue. Maybe just luck?

Should I use a Sanding sealer or just use the first light coats of 2k poly as a sealer?
What sealer would you recommend under 2k Poly?
Urethane over nitro is usually avoided. You have to be absolutely positive the nitro has finish off-gassing before sealing it in with 2K.
I suspect a polyester sealer might be more appropriate. Ideally catalyzed. 2k polyester clear sealer is not easy to source...

But is it necessary vs the clear directly applied to stained wood?
Im probably overthinking this...