yup it is very active. u can follow the account here: @postmarketOS

as for why the devices seem old: it takes a lot of work trying to get the old android kernel working with the mainline kernel. its much harder than lineageos as we dont reuse the old android kernel and a lot of work needs to be done on both the kernel and userspace

basically one person is doing an entire engineering departments work

if ud like the newest phone, u can get a fairphone 5