I understand that it's non-trivial to support old devices but that's part of the process. If companies like Apple can support Macs going back 7 years with their latest OS release then I'm fairly sure that LG can manage it. It's not unreasonable for customers to expect that their purchased products get updates for a number of years and LG certainly have the funds to do so. The problem is a lack motivation on LG's part. LG announced a 14.24 billion USD profit in 3rd quarter 2020, they can certainly spare some budget to ensure customers are treated properly.
webOS 6 needs to be made available to all existing LG smart tv's. The lack of updates for older models will damage LG in the long run. A tv is not the kind of item people want to buy every year or so. If LG won't support the 2 smart tv's that I've already bought then my next one will be another brand. Also support for developers is pretty bad. The documentation needs a whole lot more information, it is not kept up to date and the component manager can't pull updates as LG's servers are no longer available.