I wouldn’t be surprised if GiveWell pursues but doesn’t publish more speculative research of the type you’re mentioning.
I see that they often publish summaries of that kind of research in various places, two random examples:
Malnutrition: https://​​docs.google.com/​​spreadsheets/​​d/​​15Q3ww3vmZINDsJ2lGNlwdw3amRiiR_y2mkSkbUf1i-g/​​edit#gid=1814038446 (from https://​​blog.givewell.org/​​2021/​​11/​​19/​​malnutrition-treatment/​​ )
Family planning radio campaigns: https://​​docs.google.com/​​document/​​d/​​1_k7SBtgCOwMITTyseaz9rzWv3skb7XWts89m8oL6Wb8/​​edit and https://​​docs.google.com/​​spreadsheets/​​d/​​1KtjwUbh5za5LKkH2WDe6g8UQ3cOcaRs-dxZgGcvYnDE/​​edit#gid=18893171 (from their September newsletter)
I see that they often publish summaries of that kind of research in various places, two random examples:
Malnutrition: https://​​docs.google.com/​​spreadsheets/​​d/​​15Q3ww3vmZINDsJ2lGNlwdw3amRiiR_y2mkSkbUf1i-g/​​edit#gid=1814038446 (from https://​​blog.givewell.org/​​2021/​​11/​​19/​​malnutrition-treatment/​​ )
Family planning radio campaigns: https://​​docs.google.com/​​document/​​d/​​1_k7SBtgCOwMITTyseaz9rzWv3skb7XWts89m8oL6Wb8/​​edit and https://​​docs.google.com/​​spreadsheets/​​d/​​1KtjwUbh5za5LKkH2WDe6g8UQ3cOcaRs-dxZgGcvYnDE/​​edit#gid=18893171 (from their September newsletter)