ArcaNoae can't sell eCS as much of it is copyrighted by Mensys or their successor. Look at https://www.arcanoae.com/shop/os2-ecs-drivers-software-subscription-personal-renewal/ for upgrading your eCS and which drivers you can update.
Having worked at Mensys I know what type of contract Arca Noae most likely has. IBM licenses OS/2 via a so called ASL contract. The product can not be named OS/2 and has to have different name.
Even if its an OS/2 product, IBM legal perspective how they understand see it legally as different product. So you can not for example buy a license of ArcaOS and then run for example MCP 4.52.
While Mensys provided an upgrade license, no discount was given by IBM to Mensys for the upgrade licenses sold. Again simply because IBM does not consider eCS as an OS/2 product.
Technically its an OS/2 product, legally not....
As for using the driver package on eCS. I just wonder how much trouble its worth. So many other OS components in ArcaOS have also been updated and getting update install media with eCS
can be done with the new drivers. But its a big headache. eCS 2.1 was released in 2011. And I can not even to start mentioning how many bugs have been fixed in ArcaOS you miss out on with
eCS or Warp 4 even. I am not saying it can not be done. But its really for the brave solls :-)
Roderick