I switched to oatmilk recently for myself and have been trying to get my oat milk art at least marginal compared to my milk art. Narrowing in finally on the proper depth for micro foam. For kalifia barista blend it is quite deep, and oatly is just a smidge higher. Had been getting nice cappuccino foam easily, but microfoam was hit or miss, mostly miss. Last few days I have been getting closer and closer but last night was a breakthrough for me. One of the following pics is from last night's pour the other is this morning. Ginkgo leafy one was last night and I got over excited on my wiggles and flopped a big bit of foam. This mornings though was best I have managed with oatmilk.
Now that I have the trick though it will get better. Both were Kalifia farms barista blend which has been the most challenging oatmilk for me.

There is a slim window on depth. It needs to be deep enough to just get a whisper of sound no frying bacon pops at all. But if you get it too deep it starts screeching. Key is to move it to keep it in that whisper range as it doubles. Stop around 130 degrees. Higher temp and large bubbles will start forming rapidly. 3 seconds stretch at most in start.

Also the depth seems to help cut out the foam you get from shaking the jug before pouring in pitchers. It seems to suck the big pre foam and turn it closer to microfoam.
Edit to add. The above depth is specific to kalifia barista blend.

Oatly barista blend is a smidge less depth for whisper. Oatly has been my go to for art as it is easier to get both microfoam and the stiffer cappaccinos foam. I have just been practicing harder on kalifia since it is much more challenging and I like the flavor more than oatly overall.

I am using one hole steam tips on a La Pavoni Stradivari Pro and a gen 3 La Pavoni pro. Both basically same steam performance. One set at 1 bar (factory). The other .8 bar. So not near the steam power of many machines.

The right sound is what's important so if you get that you have found a good start. As it doubles it shouldn't be large movements to keep in that zone. It will be a slow move, semi-continuous.

Edit to add.

I am steaming mostly around 3.5-4 ounces usually. Taking it up to 6 makes for a longer run at texturing. I just don't like to waste milk if I can help it and mostly drink from 6-7 once cups.