Just use Google's API:
Yes, that would work great for public keys. I would think any of the "a lot of bitcoin QR creation tools" mentioned by the OP could do that. Him mentioning "secure" makes me think he's wanting to make a QR code for a private key.
Yes, it makes me wonder whether it is safe to generate bitcoin QR code online since there are many sites offers this service. After googling, chose one site on top of the search (
bitcoinqrcodegenerator.w**) and then try to generate my address (bc1qf7zhzckwr2nymljs5m7tdm0qx7nwslg5sde30p)
The result was surprised me because the QR code generated refers to address (3Jqm9TynrExdKifkwdmVGfcYpz3nmQqnVT) I have tried it 3 times, still generated that address. and then I thought; maybe it is another address of mine, connected. Check it through blocktrail. But it totally different address.
Tried another site,
bitcoin-qr-code.com/qr3 but the result is disappointing as well.
So, this is probably why OP ask it in the first place.