I am developing a custom module to add the custom filter in left layered navigation,currently we have custom product collection and want to add the filter in layered navigation with three option:
1.All Product 2.Available Item 3.Sold Items
On forum I got some useful link https://magento.stackexchange.com/a/103453/24878
and tried to add same as the described in this link but it seems this link is old and not working in current Magento version 2.3.4 .
If anyone work like this type of work please share me so I can implement in my code also.
Please share you ideas.