Do you guys just sell your prints in one material or do you let the customers pick which material? If you let customers pick, where do you add that option?

I was having issues using upscale and the image still being nowhere near big enough. I came in here to try and find help and I can see that many many others only over the past few days have been having the exact same issue. Do you think someone could make a quick guide dedicated to the process of how to upscale properly so the file size is big enough for big prints but also so the file size isn't absolutely huge, all without losing quality? It gets a bit confusing lol. I think a short guide would be massively helpful and appreciated!

1) create image in Midjourney, click creative (upscale) and download as PNG 2) use Upscayl and upscayl x4. (I’m finding that the file size after Upscayl is between 80-106mb depending on how complex the design is). This won’t go into canva unless the file size is reduced. 3) Import into Photoshop A0 template (841 x 1189mm) set to CMYK, set resolution to 300 pixels/inch. Is this correct? When I go to export it, which settings do I need to make the file size significantly smaller as a JPEG? I’ve read comments on here that it needs to be a certain size for Printshrimp (and to be imported into Canva as the limit is 25-50mb?)

Made my first print on midjourney, I upscaled it like Tom said to do and when I downloaded it, it said the image is 1824 x 2592px at 96dpi. Is this the correct size? Will this stretch up to fit big A0 sizes etc?

I'm starting my shop soon, I'm gonna make posters in different niches, I'm wondering if its better to make a seperate shop for each niche or just have one big shop? I seen a shop earlier with over 10,000 products and they just had everything in one shop with 10k+ sales only in a few years. I feel as though if you just kept 1 store and got more sales and reviews then it makes your brand look even better. What do you guys think?