The Exhibition has listed the measures they'll take to ensure the safety of attendants with regards to COVID-19. Those include:
-Controlling the attendance.
-Proper ventilation.
-Regularly disinfecting the exibits and surfaces likely to be touched by people.
-Staff will have to follow strict sanitary rules and wear masks, gloves and face-shields.
Visitors will be required to:
-Get their temperature measured using a non-contact thermometer. If you're above 37.5 °C, you're out.
-Wear a mask.
-Wait in line before entering to ensure the venue does not get too crowded.
-Wash their hands and follow proper coughing etiquette.
-Keep their distance from other visitors.
-Keep conversations at a minimum while in the exhibition or in the waiting line.
Anybody not feeling well or looking ill will be refused entry. Anybody who's been in contact with a sick person less than two weeks prior is being asked not to come. People at risk due to advanced age or medical conditions are being advised not to attend. People who have purchased tickets but get turned away will not be refunded.
Of course, they've also reiterated that the event may be delayed or canceled without notice depending on what measures the government might implement in the coming weeks.
Additionally,
@Walter found this yesterday, some merchandise that's not on the official website yet but seems legit:
https://7net.omni7.jp/fair/daiberserkten
There's a few items listed (a wall scroll, a folding fan, a zippo lighter, a bookend, a panini sandwich maker...) but the showstopper is a giant folding screen (pictured above) that's being sold for two million yens, or approximately $20,000. It's 1.72 x 3.45 meters and is a representation of the Eclipse. Limited to 10 units total, but frankly it's hard to believe anyone would pay that much for it.
The official website also has some new merchandise listed (notebooks, pens, bags, neckties, a cushion...) and I'll try to condense that into a comprehensive post at some point soon, but I don't want to do updates every other day. Also if anyone's wondering, the website is still unavailable, and Hakusensha hasn't answered my email inquiring about the issue (which affects all of their self-hosted websites, but not those on AWS).