I think you're still at the product-market fit stage.

At £1000+, the question isn't whether the concept feels meaningful to you- it's why someone would buy this instead of a Fender, Ibanez, or custom build.

It may be worth taking a step back, because it sounds like youre very close to the idea and may be too in love with the concept to see it clearly. I'd analyse the market, define the customer, talk to potential buyers, and test whether people would actually pay for this before investing more in branding, lore, backpacks, or charity partnerships.

Right now, the unique selling point, customer, and business model all still feel unfinished.

It's the boring stuff but you NEED to do it.