You'd really need a loaner for that, and to spend some extra time to set it up (and later to clear it out and return it).
I think they need to figure out how to turn these things around a lot faster at least in the great majority of cases.
It was going to be like a week to make an Apple Store appointment. I was able to walk into a local Mac shop on Apple's list of official service centers. At that time they sent it to the same offsite shops for service and they said it would take 1-2weeks. I asked about a loaner or if Apple had any sort of program since I need something in the meantime (even with different specs). I know Apple has a 14day return policy on new hardware, but I hate to abuse that. That local Mac shop was able to work something out with me with some refurbs they had on hand, but I don't think their supervisor was happy about it.
I got my computer back 5 days later. Since then, I've heard theres been a push to do more of these kinds of repairs in store to decrease the turnaround time by a lot.
A lot of this has to do with the original design. Old cars had oil filters you could take off with your hand, then you needed a special tool, then a stick thing with a strap, then you needed to take something off before you can use that tool. Apple keyboards used to lift up to expose the RAM, the batteries could be removed by sliding a tab (this was when the battery life was only a few hours and the life of the battery was like 200 cycles). Personally, I was much happier when maintenance was somewhere between that and what we have now.
In between we had canister style filters (like on my old Toyota) which may or may not require tools to remove depending on the incompetence of your mechanic. I've never seen an oil filter that needed to be installed so tight you need a tool.
Last time my battery ballooned, I had to risk turning it on and wiping my hard drive first.
The reason is that I have been asked for my password before and they wouldn’t accept my MBP for service if I didn’t give it to them.
If they still need your password to repair your computer, they really need to update their procedures.
Back then I just winced, gave them my password, and crossed my fingers (seems to have worked out), but these days I just couldn't do that. There's all kinds of financial and identity stuff in there.
Sure enough, after a few days I get the laptop back to see the hard drive's been wiped, supposedly because there were errors with the OS installation, though there were none that I picked up actually using the device.
Not that it's possible with Apple devices anymore, but that taught me I should have just given them the laptop without the RAM or SSD installed at all.
I sent my MacBook to an Apple store a few weeks ago, and it only took a few days to replace.
I have a Genius appointment and if they tell me 1-2 weeks I'm telling them to bugger off.