There are several reasons why very few companies makes a dedicated .22lr pistol that is all steel.
1. Cost
2. Engineering
1. Cost. Steel is expensive, most people buying .22lr pistols want them to be cheap otherwise they would just buy the 9mm version.
2. Engineering. Steel is heavy, and .22lr doesn't have enough energy from blowback to move a full steel slide from a full sized pistol. The Browning 1911-22 gets around it by being 85% smaller than the original, the CZ 75 kadet kit has just a tiny portion of the slide actual recoil backwards. Otherwise most .22lr pistols use a lighter zamak alloy for the slide, or have just a small portion of the slide move or use a strong polymer. There really is no way to have a full steel slide and .22lr go together.
Otherwise GSG makes the GSG firefly which is very SIG P226esque pistol in .22lr.