Personally, both digital and non-digital game design should be welcomed in game jams unless the jam's style is specifically for one or the other (ie. One-Page RPG jam, Godot game jam, etc). That being said, I am well aware to many people, the "game" part of "game jam" means digital only. Since I can't seem to find anywhere in the rules here providing a definitive yes/no on if non-digital games would be allowed, I thought it might be best to just directly ask.
It would definitely be hard to get a non-digital game into a (assumably) global game jam, just because it would be a lot easier for the people hosting the jam and the people voting in the jam to play a digital game since it's easily accessible for everyone no matter which part of the world they are in (unless they have poor internet connection or they have no access to a device, ofc). I'd say it depends on the way you choose to interpret submitting the non digital game onto the platform. If you are talking about a card or board game, you could record a video of the game (rules, how to play, gameplay footage, etc.) and send it directly to the jam discord (people could watch it in the discord), because I'm pretty sure sending a non-digital game through this platform would require delivery (local) or overseas shipping (global, but I don't think itch.io is able to do that yet lol) due to potential geographical differences, but I guess a game is still a "game", whether you choose to make it digital or physical. In summary, I'd say make a digital game just in case (in this current time, the jam starts in 2 days) but I do believe that non-digital games should be accepted in game jams as much as digital games, but it depends on how you send it to the jam. I haven't been on this site for long and I'm not sure if videos can be sent through itch.io, and while it's not actually a host in the jam replying to this so it's not really official, I hope it helped in one way or another :)
So, itch isn't a platform only for video games - assets, tools, albums, books, comics, physical games, and really just about whatever someone wants to post as a project can be found on the site. When searching through projects, that's why there is a drop down box at the top of the page to separate what kind of projects you're searching through. Switch if from "Games" to "Physical Games" and you'll get thousands of examples of TTRPGs, board games, card games, one-pages, etc.
Which brings me to another point, physical games aren't only boxed board games and card games, like you see in a store - it's just anything that doesn't require code to play. Which, if you wanna make the argument of accessability for people regardless of accessable tech - loading an image to see the rules of a game is *waaay* simpler for a device to do than trying to load and run code.
Sure, you could make a game that requires a board, pieces, extra bits, or what have you - but that doesn't stop it from being accessable on itch, or suddenly make it require shipping to play. Say you need a board; you can simply post the image file and players could just print it out (or if they are playing virtually, say over discord, one player could stream having the image file in a paint/photoshop -like program where you add and move the pieces on another layer).
That being said, a lot of the physical games you see on itch, especially those posted to game jams, don't require a ton of stuff like that. If it's an TTRPG, the most you might need besides a PDF for rules is a piece of paper, a pencil, and some dice (all of which can easily be replaced digitally, for free, if the player wanted). One-Page games are literal designed with the philosophy of "all you really need to do is to print 1 piece of paper," or, heck, just load an image of said paper (there is currently a jam specifically for these sort of games going on if you curious about learning more and want to see examples). Having multiple players (a common assumption when discussing physical games) isn't even a real requirement - solo physical games exist just as easily as solo digital ones.
As for actually posting and participating in a jam (especially one with voting): yes, you can post videos to itch on a project page or for a devlog on a project (or, bare minimum, put a link in a comment or the project's description), so if you wanted to include recorded game footage, you can. That being said, you don't really see that happening a lot, since (as discussed above) these games aren't really all too difficult to just pick up and play. Sure it's not as seemingly simple to the player as clicking a "play" button and the game running (assuming the game was designed for browser play and the player has a device that can run it - which is not always the case, or arguably the case most of the time), but in most cases all that's required is loading an image or downloading a PDF, doing some reading, and MAYBE getting some sort of physical component like dice, playing cards, or a notepad, assuming they are even needed (all of which, again, can easily be replaced digitally).
TLDR: Itch isn't just a site for digital games and physical games are a lot more simple and accessable than you're implying (arguably more accessable than digital). There is nothing really stopping non-digital entries to game Jams, unless the host specifically wants it to be digital only (hence this thread - seeing as digital vs non-digital is never clarified in the jam's page).
