Accessing SFTP server via a web based dashboard

Question

I have a web based dashboard, rendered on a browser, which allows a user to gauge the state of my remote system.

Apart from a web server, the system also hosts a SFTP server for file transfers with other devices. I'd like to make use of the same SFTP server for file transfer with the remote monitoring system, instead of introducing or managing a separate stack like WebDAV etc.

The remote monitoring system, which accesses the system via the browser, does not have a SFTP client.

For reasons such as,

1. UI uniformity
2. additional software footprint
3. maintenance / lifecycle of additional software

I'd like the SFTP file transfer mechanism (file browsing, download, upload etc.) to be web-based, preferably capable of being hosted within the dashboard, maybe as a widget, ideally should be browser independent.

Modern browsers do not support SFTP natively. To achieve the above, I have tried..

1. Browser based solutions

   1. FireFTP, disabled for Firefox v.52 / 57 and above (current version is 70+), browser dependent, can only be used by Firefox fork like WaterFox or possibly FireFox ESR
   2. SFTP for Chrome, browser dependent, but poorly reviewed, and possibly launches as its own separate client, just based on Chrome...

2. Web app renders

   1. MonstaFTP - Browser independent, though quite expensive, especially if it is per server installation
   2. JScape Anyclient - Browser independent, licensed, but not maintained (last updated a long time ago), requires Java plugins on browsers, which most have disabled.

I can put a full-fledged client like WinSCP on the system, though for reasons mentioned above, I'd like to have the client within the dashboard. Is there a way I can achieve this?