Your setup is already the lowest possible with road components. If you want any lower gearing, you need mountain bike components.
Unfortunately as you discovered, mountain bikes evolved to 1x years ago. Nowadays if you want to buy a 3x crankset, you're limited to Walmart level components such as that 9 speed you found.
If you want a higher quality 3x crankset, you'll have to look around online for old stock.
And yes, the chainline will be different on a mountain crankset. It will still work though. On a triple you can't cross chain anyway, even if you have proper chainline. That's part of the reason why triples went away.
Last edited by Yan; 09-13-23 at 07:33 AM.