paul wrote:

Is there a product or method which will keep the wood as light as poss
and highlight the grain ?

Using beech or maple instead of oak.

Finish it with wax over oil. I'd suggest Liberon's off-the-shelf blend
of both - the "Neutral" wax is lighter than the "Clear" and their tung
oil blends won't yellow in 6 months like linseed will. Of course you'll
get some darkening, but no more than anything else. There are sprayed
water-based lacquers that are lighter, but it's really not worth
chasing it.

Oak just isn't a pale timber, especially not when it ages. Don't use
oak if you don't want it oak coloured.