G2 has a list of all the software products in this category, ranked by easiest to use, etc...
Can compare the products side by side, depending on how many endpoints you have, you may be able to pull this off for free or very little
Many of these are cloud/agent based, which you will want if you do not plan on maintaining VPN to each site. And are designed for MSP and multi site layouts, so yes, grouping together by organisation is possible in most.
u/Ceyax thank you very much for the mention and the recommend.
Our cyber Monday sale allows anyone to convert their whole patch management system for free for as long as their current contract. So yes, still free for ever for the first 100 endpoints (Workstation OR Server) or a great deal to get off other systems to come see what Action1 can do.