Couldn't you... use basically moonshine?
Like, set up a distillery, get your grain mash and sugar... now you have very high proof alcohol.
Now, you could just strap basically a pilot light to ... a more seriously designed super soaker... and you'd have to add some kind of ... jellying, gelling? agent to the moonshine to get it to act more like a flame thrower than a squirt gun...
This would not be a 100% organicly sourced entire flamethrower, but you could at least make the fuel mostly, if not fully, from organic, non petroleum products.
A foot like this is a blend of decorative and functional, imo.
You end up with more surface area than if you had just gone with a straight column, and that helps with stability, slightly lessens the pressure.
Many modern tables or desks have... much less ornate footpad type structures, if the thing itself is quite heavy, or intended to hold a decent amount of weight.
Of course... I have no way of knowing if this old... desk? table? whatever it is, was intentionally designed with that in mind, but the function is still there, at least to some degree.