Is it bad that puppy won’t use chews/play/eat in play pen when I leave?

My almost 6 month old pup and I have been working a lot on his separation anxiety (had him for 7 weeks). He's now pretty okay if I leave him in his play pen and go to another room to WFH, but he won't engage with anything in his pen (food/water/kongs/toys/safe chews) unless I'm in it with him, or sometimes if I'm right outside of it. I'm trying to help him learn alone time/independent time is good but since he doesn't engage with anything, it's hard going. He naps or lies there looking sad. He WILL play/chew outside of the pen so it's not the items he has access to.

If I'm in the house still he will settle down on his own now (sometimes immediately, sometimes it takes him 10 minutes or so) but if I have to leave he just barks the whole time. I'm trying to avoid him getting above threshold but it is unrealistic for me to never leave him alone ever and yes I have tried ALL of the things and we continue to work on them (rewarding calmness, Door is a Bore, kikopup's videos, leaving for a short time and returning, etc.). The fact that he is now okay with me being in another room is honestly huge progress, but how can I encourage him to use the things in his pen? I feel like that would really help him for when I have to actually leave.