When shopping for a new dimmer to replace a rheostat model, make sure
to specify an electronic dimmer.

I would challenge you to find one (for residential use) that ISN'T an
electronic (triac) dimmer! They've been that way for decades.

The only dimmers that aren't are the variac (variable transformer) dimmers
which are very large affairs which I've never seen in residential use.
They are, BTW, superior in terms of putting out a normal AC waveform, not
the weird stuff a triac dimmer puts out. As for a rheostatic (resistance)
dimmer, I've never seen one outside of an old theatre stage lighting board.

(Technically the knob or slider you move on a triac dimmer is a variable
resistance but it's properly called a potentiometer as it is handling only
a control voltage not the actual power throughput which is what the term
rheostat implies.)