As you know, PureOS is not distribution that supports WineHQ out-of-the-box:
Please follow my draft recommendation, copy/paste from above, if you want to use WineHQ with modifying PureOS (by adding packages and repositories that are not supported with this Linux distribution). As well, here is WineHQ link that you started to follow but made key mistake with: --add-architecture 1386.
Another fine-to-coarse approach, that might work (as I don’t use it) quite well, would be to install winepak (https://www.winepak.org/), but first you’d need to install flatpak (Flatpakâthe future of application distribution). Please reply here which solution (WineHQ or FLATPAK based) was adequate installation method for your needs.