Switch – After replacing incandescent bulbs with LED bulbs, why am I getting flickering from some of them, but not all, on dimmer switches

It makes sense - look for "low voltage LED Lighting" to see what's available, or slide on over to Electronics to build your own.

Dimmable LED bulbs are those with drivers built-in that are "dimmable" - if just running controlled current to LEDs, they are all "Dimmable" (lower current, lower light) so, no, you don't want an LED described as "Dimmable" (nor one described as 12V, probably - a "bare" LED with no other parts attached is best when you are going to feed it controlled current.) If you purchase a "12V dimmer" pre-made, follow the dimmer-maker's suggestions on types of LEDs to attach to it.

LEDs are current devices, so controlling the current will give highly consistent light output (controlling the voltage, less so)

Here's a photo of the bulb in question:

I have that same bulb and when used in a shade that hides the bulb itself, it does radiate similarly to an incandescent. The bulb has an array of small LED's around the edge that light up the thicker ridge of plastic, it essentially looks like a bright tube of evenly lit light, so the light radiates in all directions. However, the thinner plastic in the middle isn't lit. Since the entire ring is lit starting from the bottom of the bulb and the ring is wider than the base, some light is radiated downwards, but like a traditional bulb, more of the light ends up going upwards since the base blocks some of the downward lighting pattern.

This unusual shape can be visible in a lamp with a translucent shade or in a fixture where the bulb is exposed. In a lamp with a traditional paper (or paper-like) shade that is nearly opaque, this type of bulb has a very even light distribution.

Here's the light at a low dim level, showing the LED's around the ring:

But when the light is at full power, they all blend together and project light evenly, lighting up the entire "tube".

I tried these bulbs in a bathroom fixture, but discovered that the translucent shade on the fixture was transparent enough that the bulb shape was quite visible, so I replaced them with more traditional looking LED bulbs.

Since the floor lamp you're using has the bulb above eye level, as long as the shade is sufficiently frosted to prevent the bulb shape from showing through, it should work well.