Yep, I believe you are over thinking it. Those appliances might have been stored somewhere else in less favorable climate and conditions before you purchased them anyway.
We just completed the remodeling of our kitchen. But what got us moving forward was going out to HDepot and looking at the type of gas range we might want to replace our double wall oven and cook top that we had in our old kitchen. That was in April 2021, and when we found that the range my wife liked was on sale to the tune of $1K off when there were very few appliances on sale due to the lack of availability that Covid factory shutdowns combined with the passing out of free money created, we just purchased it right then without even having explored what it would cost to remodel the kitchen and who we might hire to do the job.
Then right after that we also bought a new refrigerator as well. We put off the delivery as long as we could, until early Fall, but then stored them in our garage from that time until the kitchen was nearing completion in April 2022, last month. We signed our remodeling contract in July 2021 with the expectation that the cabinets would be available in approximately 15 weeks (some time in October/November), but our contractor overscheduled himself as many do and then seemed to drag out the work from a 1/24 start to only finishing this past week. One of the big delays was the quartz counters and backsplash supplier. They first measured once the cabinets were installed, but it was 3 additional week before they were ready to install the countertops. Only then would they measure for the quartz backsplash, with the next 3 week delay until they came back to install the backsplash.....
I can't imagine why sitting in a garage, unpowered, would have any effect on the performance of an appliance for the long term. But we did leave the appliances in the boxes they are shipped in to keep the dust and any fumes or dirt off of them. Electronics could be impacted by excessive dust in the even the dust/dirt got into and onto the actual circuit boards, but that should not happen if you keep them covered in your garage.