There seemingly exist no dedicated Christian-curated and maintained appstore for the Android computing OS, sadly. If the web version of the Google Play Store offered all features offered on the Play Store app, then one could simple disable images and then ever use that web platform for searching and installing application. But upon testing, I found this greatly limited and can be of no much help on this concern. The above actually is amongst valid options but only if done from a PC.
NB. We have gone on to develop a simple WebView based app that lets you access and use the web version of Google Play Store on mobile. And as hoped above, we implemented image blocking
The foregoing are alternative options: 1. Search for Play Store apps via a internet browsers and you should be redirected to the pertinent app's Play Store page upon clicking on their links from your browser. The only possible caveat should be related apps (which may not all be friendly) but the risk should be minimal. Or 2. Depend on apk service offerers like APKPure and APKMirror whenever you can safely get away with. Do kindly note that these are often ads supported (and operated by the Christless) - meaning that they should be a ideally be accessed from a browser that supports both ads as well as images blocking (such the LC Browser) as we sadly cannot vouch for their cleanness. Several caveats exist for this approach as well - such as a somewhat limited list, version differences, etc but it is a very valid option. Only do be sure to stick with fairly credible apk providers such as the above mentioned as this can be a sure way to usher in malware, adware, etc onto your device if the wrong apk is used.
The likeChrist Ministries does wish to build and maintain a multi-platform appstore for these very concerns should the Lord permit. We must however first try to verify the possible efficiency, practicality as well as ensure that it indeed be no project that is already undertaken by another biblical Christian.