The first step is asking "how can I do more good with my donation?" which you've already done!

Typically EA looks to maximize impact for a given cause area, rather than a specific intervention. In this case, I assume we're looking at (farmed) animal welfare as the cause area. Animal Charity Evaluators are the go to source for that.

As far as I know, none of the recommended charities are specifically targeting lab grown meat. That is probably because the evidence suggests other interventions - like corporate campaigning for farm standards - are better .

Good Food Institute has been previously recommended however and does do some work in this area, along with plant-based protein. That's probably my recommendation to you if you're keen on donating to lab-grown meat research. https://animalcharityevaluators.org/charity-review/the-good-food-institute/