You might also want to take a look at jt-ipam, especially if you're using Proxmox VE.
jt-ipam integrates directly with Proxmox VE and lets you open the native Proxmox console directly from the VM/CT interface — noVNC for VMs and xterm.js for LXC containers. So for many cases, you can simply find the VM or container in jt-ipam and open its console directly, without looking up its IP address or configuring RDP/VNC separately.
It also provides centralized VM/IP inventory and infrastructure integration, so the console access is tied directly to the VM or container you're managing.
Apache Guacamole is still a good choice if you specifically need a centralized RDP/SSH/VNC gateway for accessing guest operating systems. But if your main goal is one-click access to Proxmox VM/CT consoles, jt-ipam may fit your use case quite well.