I see. Thanks guys for the well explained answers. I'm a bit confident now to use what I've setup. Tho I might still try and test it first with small amounts just to be sure I didn't miss anything.
I've got no further inquiries.
After testing if you are actually using it for the large storage of funds I will advise two things.
1. After the test is done and you understand everything, do not use the exiting seed phrase or keys, just create a new one and then transfer all funds there to eliminate mistakes like the seed phrase or private touching the internet probably because you lack have knowledge before and make sure you do everything offline.
2. I would advise you take extra cost to get another device so that each co-signer will be on different devices even though this your current set up isn’t bad but this one will be more secure. And this time the devices should be airgapped to eliminate any chance of compromise.