I have a variety of automations running which print actionable tasks to my receipt printer via a Raspberry Pi. It’s nice having a real-life ticket I can take hold of.
One thing to be aware of if you’re handling receipts frequently: make sure to buy phenol-free thermal paper. Phenol is toxic and some types of it are banned in certain countries.
Since I’m in Europe, we don’t really have paper with bisphenol anymore, but that’s not the case everywhere.
If the substances used are known to be toxic is another matter but you won't know that even with a correct label because it takes time for us to find out that new substances are toxic.
To the GP, if the goal is to avoid phenol papers, phenol papers tend to develop deeper black. And in the US, phenol-free papers are new enough the backside often advertises it. Some are very misleadingly labeled BPA-free, which usually means it's made with the very similar and likely equally toxic BPS.