One thing that is worth noting about Meilisearch is that it seems to only allow high availability mode in their hosted cloud service. In their comparison matrix, under deployment it shows high availability as “available with Meilisearch Cloud”.
Overall it seems like a promising product, but for anyone running a non-trivial deployment of Open edX it would force them into using their hosted product. In general that may not be a show-stopper, but I can imagine there are cases where that would prevent someone from using Open edX.