Brick/Flag Sealant for Fireplace

Hi Group. I have a old brick-lined fireplace with york stone-paved floor. I'd like to seal the crumbly brickwork and the flag floor to keep in the dust, protect the material and hopefully, bring out the natural colour of both. I am hoping to keep a matt, rather than gloss, appearance. The fire in question is a recently fitted Multifuel stove.
Has anyone had any experience with this? Google provides a few suggestions - dilute PVA sprayed onto the surface; BourneSeal Natural (which I can't seem to locate); and a water-based stablizing solution. However, none of these seem to have universal approval.
Any suggestions or experiences related to this would be extremely helpful.
Thanks! Jon.
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