Just a hypothetical - if one used a LUT on an adjustment layer above everything and then graded everything so that it looks good with the LUT and then exported a 10bit file without the LUT, could this be used as HDR output?
Theoretically, yes, as long as the export is flagged as HDR. This can be done in Resolve under the color management settings.
However, when producing HDR content, in order for it to be worthwhile, it needs to be created using an actual HDR monitor. Otherwise the film could end up looking fine in SDR, but then looks totally different than intended in HDR. (You’d basically be doing an HDR grade blindly).
While decent SDR monitors for content creation are relatively cheap these days, monitors for HDR content creation are still very expensive - like the Sony X300 or the FSI XM310X. Although some prosumer displays are starting to get pretty good - like the ASUS ProArt PA32UCX and the Apple Pro Display XDR. (Still expensive though).