Hi Derek,
I'm not an attorney, and it sounds like it may be in your best interest to involve one before investing in this type of business.
However, I can share some thoughts. Feel free to consider them when further researching this business opportunity...
Magento Open Source (Magento Community Edition) is open-source software. As such, I can't think of any compliance issue that you'd have that would be specific to Magento, but you can further review Magento's licensing and any other published terms.
There are existing multi-vendor extensions for Magento that allow you to go beyond a traditional eCommerce site and allow multiple sellers to sign up. You can see some of them here: https://marketplace.magento.com/catalogsearch/result/?q=multivendor&ext_platform=Magento%202
Given the types of products you've suggested, you may need to create strict policies and oversight to make sure that sellers don't add any products, product details, or images that touch on anything that is illegal.
You'd also need to make sure that you find vendors that will support your needs. I'd expect it to be easy to find a web host that will be ok with selling these products. However, you might also need to find a payment processor that will work in a multi-vendor (split payment) fashion, and also support the sale of the products your site would be selling, which sound like they'd be considered high-risk by many credit card processors.
Additionally, you'd need to consider your marketing plans to onboard sellers and buyers. Keep in mind that some marketing channels, like Google Ads, may not allow you to advertise, as they block ads that relate to certain products.
While I understand the angle of selling handmade artistic glass, if it looks like something used with tobacco, or marijuana, it may violate the terms of service of some vendors. In some cases, you could be initially approved, like for paid ads, just to be disapproved later on after you're up and running. I'd recommend reading the terms of service of any company that you're considering relying on.
As an example, here are terms of service from Google, which specifically prohibit running ads when pipes, bongs, etc. is involved: https://support.google.com/adspolicy/answer/6014299?hl=en
Similarly, PayPal limits the products that they'll allow you to sell using their service to collect payments: https://www.paypal.com/gf/webapps/mpp/ua/acceptableuse-full
If these are fragile items, you'd also need to think about return policies that sellers would need to adhere to, and any other shipping standards and expectations to avoid your marketplace getting a bad reputation and/or chargebacks.
Overall, I can see why you're not finding more websites selling these products. It's a more difficult niche to work with online.
Best of luck in your research!
