Last month I had a chance to try a new addition to Priority Pass, the Osaka Airport Winery. I talked to the *brewer* and indeed, they ferment the wine on premises. PP gives you a set of some tasty light food and all-you-can-drink from their list of about six or so wines. It's not Romanee-Conti, for sure, but still fun to try. Previous options at ITM were pretty basic.

1. Cardholders can use their lounge visit entitlement for a maximum of a 2 hour stay to take advantage of 1 set menu designated by the restaurant including unlimited house wine or 1 soft drink.

That's good news. This, along with next year's opening of a Centurion Lounge in Haneda Airport, are welcome new developments. I hope more airport restaurants in Japan join the Priority Pass program.

The restaurant option is certainly much better than the lounges, given the normal domestic lounges just provide soft drinks and maybe a candy or senbei if you are lucky.
KIX also has landside lounge access that is PP. Just two beers and a dish of food, but better than nothing.
Narita has a couple options. At least one is landside and offers a decent okonomiyaki set.

I was on the fence as to whether to renew my Rakuten Gold card, as the only real benefit is the PP access. Just cardmember (guest is �3,300 and rarely worth it), and starting in January it will be limited to 5 visits a year. I consider a domestic lounge visit worth about �500, but the restaurant visits are decent meals, so getting 4 or more makes it worthwhile.

True, the majority of domestic airport lounges, especially outside Tokyo and Osaka, only offer small bags of senbei as food. I've visited the PP Lounge (actually, the KAL Lounge) at Fukuoka Airport. Though small, even they offer more food than you'll get at a standard ANA Lounge. BTW, the Osaka Airport Winery shows up in PP app, but under its condition, you cannot bring a guest with you, which you can at most PP restaurants in the U.S.

True, though your companion is free to order a (paid) drink or food and sit with you.
With other PP places, Rakuten charges me �3,300 for a guest, which is often not worth it.

I have a flight arriving ITM in a few weeks and want to give this one a try. On their website, it says that the PP card and a BP of same-day departure (当日出発の搭乗券) is required, while on Priority Pass it just says a BP of same-day travel. Am I correct to assume that my HND-ITM boarding pass would allow me to use this restaurant?

Should work. I have used PP on arrival and predeparture a few times.

Unfortunately my inbound flight was delayed and got to the �winery� a few minutes past 9, only to see a CLOSED sign by the door. Their last order was actually 9pm and not 9:30pm as shown on the website.

Sorry to hear that.