I have used 4 RaspberryPi (3 and 4) for a few years for various needs : Gitea server, Home Assistant server, Syncthing main repository, Borg backup repository, Wireguard VPN and network gateway between 2 LANs. I haven't encountered any problems with the SD card, if you buy the class 10 SD cards (the same you would use for your dashcam and security camera). One option is to use the F2FS file system on the card (I did this on my Raspberry) or, as others have suggested, use an SSD or NVMe drive. The main problems I encountered with the Raspberry 4 were heat dissipation (use a metal case with direct contact to the CPU without a fan, this is the best option in my tests) and external USB 3 drives interfering with the wifi. The latter seems to be a known design issue. Considering all this and the prices, if you don't really need the Raspberry's ability to control external hardware via GPio, and if you want to keep the same network design (separate devices), there are many mini PCs with passive dissipation, 2 or more Nics, lots of RAM and SSD support, for a similar or lower price all considered ... or buy one or two real servers and virtualise everything with Proxmox.