The color primaries and matrices of BT.2100 are identical to those of BT.2020 so the tags are not replicated, but as I said BT.2020 is not an HDR format. The codec is irrelevant. You could equally flag the video essence as BT.2100 PQ with no metadata or BT.2100 HLG (which doesn’t need metadata) and TVs would switch to the correct mode.
HDR 10 is a distribution format which adds metadata to the PQ production format (as are HDR10+, Dolby Vision, SL-HDR and most of the Dolby Vision classes), it’s not really needed in the editing process.
Any editor working in HDR needs to be able to import BT.2100 HLG, BT.2100 PQ, BT.2020 and BT.709 files and map them to a common timeline format, output to those 4 formats, and allow the user to calculate the HDR10 metadata if you choose to have a PQ output format (this isn’t automatic as you need to know the gamut and peak brightness of the monitor you edited on).