Two domains, one shopify store - SEO question

Hi guys,

I have one question cause I couldn't find clear answer and I hope you can give me a piece of advice.

I have a shopify store, let's say 'coolhandgloves.com'. A few days ago I realized there was one domain available to buy, let's say "leatherhandgloves.org'. This .org domain has nice PA/DA values and has already links from some other, similar websites (however, there's no traffic, only SEO value).
The first, .com domain is the most important one, this is my brand name.
I am wondering how to use .org domain to strengthen the main .com domain.
1. shopify allows multiple domains. should I connect .org domain to the shopify store? in this way shopify redirects .org to .com. But does it count for SEO?
2. should I create some site based on .org domain with blog posts about various products from .com store and d0foll0w links to .com domain?

Thank you in advance.

What you do is a 301 redirect to your main store, OR you can redesign the domain into a PBN and link to your main site.

oh, ok. Then I guess if I assign a few domains to one shopify store and set a primary .com domain, it's going to be treated as 301. At least according to some shopify discussions.
However, if there are some bad/spam backlinks to the .org domain, my .com domain is going to get hurt..?

Tell me if I'm wrong but I guess PBN is more secure but also more time-consuming.

If it is relevant then definitely do a 301 to your money site.