Thanks for gathering some details on the existing GNO liquidity sources. This does indeed seem quite comprehensive and I would also vote in favour of such a proposal.
It is worth noting that this is a long outstanding GIP-8 (GIP-8: Enable LP token voting on Snapshot) that addresses this very same proposal - although it is rather outdated and the current liquidity is in many different places now.
I don’t think any GNO holder would be against such a proposal, but I suspect the reason it has stagnated for so long is that we are still lacking a concrete implementation plan.
Integrating such a feature, while entirely possible, would require infrastructure for determining exactly how much GNO should be credited to the LP tokens at, say a given moment in time. For traditional AMMs such as UniswapV2 (and similar) or even Balancer this amounts to fetching the pool reserves, the total supply of the LP token corresponding to the reserves and computing how much GNO corresponds to 1 LP token. This is relatively straightforward, but it gets a bit more complicated when trying to perform the analogous share holder representation for Uniswap V3 liquidity - since the LP token is actually an NFT representing how their liquidity is concentrated along the curve.
As a community member, I would be very keen to see this happen and willing to contribute some time to assist with implementation planning. However, I think that providing a concrete plan would be required before moving into the next steps.
Another thing to note is that we would likely have to introduce just a few liquidity sources initially and as time goes on, depending which sources remain substantial/relevant, add support new ones as the ecosystem changes.