I've dabbled with Hubspot's free signature creator and Wisestamp, although both are missing certain aspects of customization. I've come across a few others that require a CC to trial and that's turned me away immediately.
Ideally the final signature can be exported in both plain text and HTML.
We’ve used Sigstr with some success! It’s easy to use but it can get pricey with limited ROI. It’s worth checking out though
@NBNite You can download DoNotPay app: https://apps.apple.com/us/app/donotpay/id1427999657
Which will take care of the free trial problem with trial cards.
For G Suite, I would recommend BetterCloud, which offers far more than just email signatures, as it's a full cloud management tool. It was a little expensive, but worth the money.
For O365, I found Exclaimer to do exactly what was needed. It applies a templated signature as you send an email, via mail transport rules. It wasn't possible for the sender to see the signature when writing an email, if I remember rightly, that was the only downside.
Markdown is the most popular way to format plain text. Add common characters like asterisks and dashes to text, much like how you might format a quick store list in your notes app or add emphasis ...
Or do you use the Linux subsytem in Windows, emulation tools like DosBOX and WINE, or mobile device emulator/simulators? What's your favorite ways you've used virtual machines and emulation?