Advice requested - external drive setup

Here's a little background. I've been using Macs exclusively for 15 years, and about a year ago my Macbook Pro had some kind of catastrophic error that Apple couldn't fix. I was using Time Machine at the time, so luckily I didn't lose much. For the amount a new Macbook Pro would have cost, I briefly considered building a gaming PC as a replacement. Unfortunately my only backup was on Time Machine and I had no other Macs, so I was locked into getting another Mac. I got the cheapest Mac Mini available (with internal storage far below my needs) and invested in an external 1 TB SSD. Since my wife only has a PC and I wasn't sure how long I would stick in the Apple ecosystem, I formatted the external as exfat so I wouldn't run into an issue with it being read on a PC in the future. I figured this would give me the greatest amount of flexibility going forward. Everything is saved exclusively on that external drive (nothing of consequence on the internal), and since I can't back up the exfat drive with another Time Machine drive, I got a 2nd identical exfat external SSD and have just copy/pasted everything over once a month as a backup. Today I was considering getting a larger capacity drive, and in researching came across more than a few comments mentioning that while exfat can be read on both Mac/PC, it is more prone to issues where I could lose data. With the amount of irreplaceable work and personal files on there, the thought of losing part of it or everything made me feel sick. I think I have an idea of how I want to proceed to best protect myself, but wanted some outside input before I spend a lot of time doing something which might be pointless, or not the best course of action. My new plan: 1. Copy my SSD to my backup SSD and ensure all files are present and functioning. 2. Format my SSD to a more Mac friendly format (would APFS be best?) 3. Copy all of my files from my backup SSD to my regular SSD now in a new format (please tell me they would all copy over without issue here.) 4. Continue to use an exfat drive as a backup for the same reasons described above (would the Mac format drive be able to play nice while copying over to the exfat drive consistently?). 5. Add a 2nd backup drive to use as a Time Machine backup (this time a 4 TB HDD), which should now work with my external SSD since it will be in a Mac friendly format. Confirmation that this plan would work best would make me feel a lot better before proceeding, or if anyone had some alternative advice I would greatly appreciate it. I would prefer to stay away from cloud solutions.