<waking up from nap> Um, wha....? Oh, okay, sure -- I can answer this!
Anything that is a triglyceride fat (and soy wax is actually a triglyceride, not a true wax) creates glycerin when you turn it into soap. After curing, the glycerin content is, oh, around 10% of the cured soap by weight.
If you use a fatty acid like stearic acid to make soap, it doesn't contain glycerin in its chemical structure. So if you want the benefits that glycerin brings to soap, you would want to artificially add glycerin to a soap made with fatty acids.
Shave soap isn't a soap that you would want to bathe with, so the objections about adding glycerin to bath soap don't apply to adding glycerin to shave soap. Glycerin helps the soap lather remain more stable, wet, and lubricating during the shave. It will also make the finished soap softer. If you want a croap style soap, that's not a bad thing. If you want a hard bar, you'd not want to get too generous with the added glycerin.
Based on the shave soap recipes I've seen and the recipes I personally use, glycerin is often added to shave soap at 10% to 15% by weight of fats + fatty acids. So if you use 1000 grams of fat + stearic acid, you'd add 100 to 150 grams of glycerin. That's more glycerin than what's "missing" due to the use of stearic acid, but it works.
More: https://classicbells.com/soap/glycerin.html
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