There is already a feature request open for this, going back to 2021:
New JXL JPEG file format - DxO PhotoLab / Feature requests - DxO Forum
DxO rarely participates in the forum - though they do look at activity here. There was a time that they would be forthcoming about development plans for something like this - however, they couldn’t stick with those plans and might have stopped communicating such things for that reason. The company I last worked for had great customer service - however, we were told not to discuss plans for future product releases. Seemed to be an industry standard practice.