Don’t confuse backups with syncing. Although syncthing has a recycle bin to recover deleted and overwritten files, you shouldn’t rely on it for guarding against accidental deletion, file corruption, or ransomware. You want something that will allow you to restore files from a point in time. There’s lots of proper backup tools for this. Borg, Restic, etc. Each has pros and cons. Make sure you test recovery. Also 3-2-1 is 3 copies of data, on at least 2 different systems, and 1 off site.

Static site generators. Jekyll, Hugo, etc. Pick a template, write in markdown.

Homebox? Create an asset for, say, your furnace, then you can create maintenance tasks, with dates and costs, and schedule future work.

I’d even recommend encryption for non-laptops, it’s less about IF they get stolen and more about WHEN the hard disk fails, you don’t need to worry about all of your personal data being immediately available to anyone who plugs in your failed disk (whether RMA’d or electronics disposal). Before diaposal, if you can, run cryptserup erase to scrub the encryption keys.

Now they are all really scammy. I haven’t found a good code in years. All those sites do is forward you to the site with a referral link, if you buy something, coupon code or not, they get paid for the referral (and possibly future purchases you make).

Best I can suggest is to attack their business model. Open those sites in a private tab, copy/paste the codes to your normal browser.