All macs support screen sharing out of the box. Can you set up a Mac at the place and remote in?
If your router supports it, have it set up VPN in so you can join the network from a remote connection and then you don't need any extra steps other then following the guide on Remote Setup.
If you don't have the ability to log in to the network itself using VPN software, on a technical level, you need a software client to broker the internet connection data if your work has a NAT and doesn’t assign publicly open IP address (IPv4 or IPv6) to your computer.
Two options are:
This is one case where you want to get permission to use this software from the company involved. You could be seen as bypassing security and opening them to data exfiltration, remote control and security breaches when you connect in without their permission.
You can write the guidelines if the company is small and start slowly. You’ll choose a strong password on your mac and only use one software and then let them review the setup once you’ve tested it. Someone either pays for internet or set up the network, so work with them and you’ll be set.
Even if you VPN in - Screens Connect is great and you can try it out for free using https://setapp.com/ and then just rent it if you don't want to buy it.
Lastly, ubiquity offers powerful networking gear if you wanted to hire network specific tools for this task. Then you could set up a point to point VPN or have work install this gear so you can securely connect if they have nothing set up for this yet.