Is it possible to set up a RDP session without FortiClient being installed?

Long story short, we have many users who have the option to work from home by accessing their work desktop PC’s using RDP. Our current solution involves staff going to a website and logging into the system using their credentials/MFA. It then downloads a small tool called MotionPro that needs to be installed locally, but once installed they can sign in and access their desktop via RDP. We have a linux box on site that provides the user authentication and session management.

I am wondering if there is a way that we can use the Fortigate and user credentials to faciliate this kind of connection without the need of the seperate linux box? I know we can to RDP over VPN, but I am assuming that requires staff to have FortiClient installed on their personal home PC and then needing to connect prior to launching a RDP session back to their home PC.

Ideally, we are looking for a solution that does not require a local install for FortiClient. We are OK if they are prompted to download a small utility at first login, but we do not want to require staff need to be connected to FortiClient prior to accessing their remote PC’s. Is it possible to cut off the linux box and set something up like this? Or would it for sure require a local VPN client to be connected prior to using RDP from their home PC?

EDIT: Thank you for the suggestions, all. We were able to successfully test a solution where staff can log into the firewall from outside the network using MFA and then remote into their PC on site using a bookmark on the firewall to that device. The issue we are now running into is that the remote session is confined to a small window within the web browser, but staff would like to utilize both of their monitors in full screen, and not a single smaller display on a single screen. So we’re still exploring solutions to work through this.