can't install pos by composer d8.8.5

I've got the same error on a brand new drupal/recommended-project install.

I'm still considering this module but I had to test the composer download to be sure. I found the reason you may be getting this error is because the dependency commerce_order is missing. My D8 install has commerce installed already before I added pos. From the composer setup, pos download includes about 20 other dependency modules of which commerce_order is one of them, those need to be enabled along with pos to work/install.

UPDATE
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https://www.drupal.org/project/commerce_pos/issues/2936480#comment-13554162 confirms the error can be fixed by using the current dev version

Hi ojchris37: I tried your solution (installing Commerce, then Commerce Order, then Commerce POS on a brand new Composer install) and it was showing the same error.

Installing the dev version is an option of course but I hope this gets fixed. It's very easy to reproduce the error.

@bramvandenbulcke it was impossible for me to uninstall pos, as I kept getting an error about a missing item (can't remember) when I tried to clear cache after the uninstall. I couldn't even manage to move around the site (website encountered error). Luckily I had a backup of the site prior to downloading/installing pos.

Once I could setup the backup (deleted the previous) I was able to download/install the pos dev with no problem. Trying to figure out the new commerce approach in D8 by setting product/variation types. Once done should be able to attempt the pos features.

This should be fixed now as part of compatibility updates for commerce and d9. I tested a clean composer install and all worked correctly for me.