In OpenMediaVault there is a plugin called folder2ram which is designed to buffer SD writes to RAM, and then write them out periodically. the use case is for NAS which is probably on 24/7. similar to a router. for some devices (NanoPi R4S rk3399 R6S RK3588S 4G is a great new OpenWrt device - #1139 by giuliomagnifico) they may not have internal flash and thus rely on microSD. is it worth thinking about caching to RAM? in this case the R4S has 4 GB of ram, plenty of room for writes temporarily.
Further reading:
https://forum.archive.openwrt.org/viewtopic.php?id=62728