activity alone is not a reliable proxy for quality

This is true, but it is a huge proxy for investment and survivability. In the beginning, it was hard to tell how much Amazon would invest in OpenSearch, but it appears now (based on activity) that Amazon is committed to OpenSearch.

Based on my experience, I can see it. I had the OpenSearch PM reach out to us because of our work with OpenSearch. AWS are investing for the long haul, here.

Yeah if you look at only changes to Java files in OpenSearch (OpenSearch + Security) and Elasticsearch, the number of contributors is growing at a steady pace and who knows, it may well surpass Elasticsearch in a year or two.

     month  |    project    | authors | commits | files |  churn  
   ---------+---------------+---------+---------+-------+---------
    2022-03 | elasticsearch |      61 |     529 |   948 |   39307
    2022-03 | opensearch    |      20 |     138 |   603 |   26042
    2022-02 | elasticsearch |     110 |    2783 |  3546 |  287818
    2022-02 | opensearch    |      45 |     582 |  1441 |  126678
    2022-01 | elasticsearch |     126 |    2431 |  3609 |  360828
    2022-01 | opensearch    |      40 |     175 |   640 |   26902
    2021-12 | elasticsearch |     103 |    1803 |  4050 |  301715
    2021-12 | opensearch    |      33 |     166 |   703 |   30182
    2021-11 | elasticsearch |      94 |    1430 |  2309 |  141589
    2021-11 | opensearch    |      31 |     119 |   932 |   44234
    2021-10 | elasticsearch |     102 |    1013 | 12589 | 1217275
    2021-10 | opensearch    |      28 |     142 |  5776 | 1256157
    2021-09 | elasticsearch |      83 |     729 |  2269 |  119506
    2021-09 | opensearch    |      17 |      53 |   126 |    8336
    2021-08 | elasticsearch |      87 |     654 |  2479 |  180385
    2021-08 | opensearch    |      23 |      42 |   128 |    3610

agree that activity is a proxy for (community support) + investment and survivability