How to approximate the Maillard temperature (154°C) in a pan?

The Maillard reaction begins around 150° C. You do not need that exact temperature. Usually, you don't even want that exact temperature; even baking temperatures usually hover around 175-200° C (350-400° F), and those temperatures are held for 20 minutes or more. Pan-frying is almost always a fast cooking process lasting no longer than 10 minutes.

Thus, almost every cooking oil has a smoke point at or around the ideal temperature. Butter is a bit too low around 121-149° C (250-300° F), but the vast majority of liquid oils - peanut, sunflower, corn, canola, sesame, even EVOO - all have smoke points from 150-260° C (300-500° F).

See Wikipedia's list of smoke points for a fairly complete list. Avoid butter and unrefined flaxseed/safflower/sunflower oil (commercially-bottled oil is almost always refined, except for EVOO).

Of course, this doesn't say anything about cooking time or sticking. When we talk about frying or sautéing in oil (i.e. to get the Maillard reaction going), we usually want a quick sear, and for that you really want to get the pan screaming hot so that you can get a good sear on the outside without doing much to the inside. Clarified butter, coconut oil, or any other of the highly-refined oils are the best for that purpose.

If you're really trying to prolong the cooking time, i.e. pan-frying a chicken breast all the way through, then I guess you'd stick with a lower smoke point oil, such as EVOO or unrefined peanut or sesame.

As you mention in your comment, 154°C doesn't refer to the pan temperature, it refers to the temperature of the thing being browned, so there's no point in being too precise with your pan temperature, which will decrease a bit anyway when you put the steak in. In any case, 154°C is only when the Maillard reaction starts; it's not like you're trying to maintain the pan at that temperature.

Just get your pan really, really hot, i.e. leave it on high heat for a good 5 minutes before you start to cook. If you really want to test it, corn oil's smoke point is 178°C, so if that starts smoking you're well on your way to browning anything you put in the pan.

Use a piece of butter. When it has just started browning, pour it out (before it can smoke), and the pan is now hot enough to brown other things.

Allow an extra minute or two for the pan to get hotter, so it's well above the Maillard temperature after losing heat to your meat.

Or, just do what most people do, and let an EMPTY cast-iron pan get insanely hot and sear the heck out of the steak.

I find that a non contact IR gun-type thermometer is a really handy kitchen tool. You can get one cheaply too:

https://www.amazon.com/Infrared-Thermometer-Contact-Temperature-Measurement/dp/B002OD0NCG