The Problem Due to the current state of affairs, you are out of work and have plenty of time to practice with your handguns to maintain and improve your handling and marksmanship skills. However, there are two problems with this scenario. The first is you can only dry fire so much until it becomes almost pointless because of the lack of feedback from a target. The second is your budget will not allow the purchase of the amount of centerfire ammunition needed to conduct meaningful practice sessions.
The alternative is to practice with a less-expensive .22 LR handgun. However, the concern here is the lessened recoil and diminished report of the gun added to the handling differences will create bad habits in the long run. Is this a valid concern or are you over-thinking the situation?
The Solution Skill sustainment with .22 LR is a good alternative to maintain proficiency with gun handling and marksmanship in general. There are several things to keep in mind that should enhance the experience further than just shooting some targets.
Even though the noise and recoil will be different, the operation of either a semi-automatic handgun or a revolver should closely mimic that of your centerfire gun. As important as anything are the trigger and sights on the practice gun. They both should closely replicate that with which you have become accustomed on your centerfire pistol. This makes what you see and feel in shooting one or more shots no different regardless of caliber.
Many manufacturers make and offer .22 LR conversion kits for their centerfire pistols. They usually consist of a slide assembly and magazine that can be installed on the fieldstripped centerfire frame in a matter of minutes to convert the pistol from one chambering to another. This maintains the same trigger pull and provides at least similar (if not identical) sights from one slide to the other.
There will be some weight differences, since the .22 LR slides and ammunition weigh less than the centerfire components. There may be some handling differences as well since many of the rimfire conversion kits will not lock the slide rearward after the last round is fired the way the centerfires do.
There may also be some other subtle differences, but these and other inconsistencies can be overcome by converting the pistol back to the centerfire mode and shooting a drill or two before leaving the range. This will leave the proper memory of how the gun sounds, feels during recoil and handles in its normal configuration.
Some manufacturers make complete pistols in .22 LR similar to their centerfire siblings that handle and operate for all intents and purposes the same. The Glock G44 and Smith & Wesson M&P22 are but two examples of .22 LR pistols that closely parallel their centerfire counterparts. Like the conversion kits mentioned earlier, these pistols are lighter and generate less recoil (and less noise) than the centerfire versions. If there is any concern about losing familiarity with the characteristics of the centerfire gun, running a drill or two as suggested above with the full-bore variants should keep operational perspective with the centerfire.
Most revolver manufacturers typically offer .22 LR-chambered revolvers in the same frame size as their centerfire models used for concealed carry or defensive purposes. As with the semi-automatic pistols, there are usually slight differences from their centerfire equivalents, but the handling and overall features are nearly identical.
Again, finalizing a practice session with the centerfire gun is a good way to stay familiar with its shooting and handling characteristics.
To maximize the training value of practicing with the .22 LR handgun, the product selected should be compatible with the holster and other gear used for the centerfire. This will allow maintaining and improving previously learned skills without breaking your budget.