That plugin is just a wrapper around a well known FOSS algorithm implementation that has existed for over a decade. (Enfuse is typically bundled with hugin but can be used standalone)
I would disagree on this for the use case of bracketed JPEGs into enfuse - it was specifically designed for this exact purpose and works quite well. So well that it’s been (ab)used to implement a general tonemapping algorithm by feeding it “synthetically bracketed” shots from an HDR raw (see Google’s HDR+ and NightSight pipelines, both depend on a slightly modified variation of Mertens exposure fusion that feeds the algorithm with synthetically bracketed shots.)
The only other option for JPEG inputs might be the Debevec approach, discussed in Python Image Processing in Computational Photography | Toptal® - but I would strongly advise against this if it can be at all avoided. Either enfuse or merge raws.