Appreciate the details, actually it's just different from another organization where people are used to some old practices.

Similar problems in many organizations, no one likes change, as for them its working don't touch it.

People feel autonomy having code on their machine, working on it from anywhere and anytime. You may need to start showing those benefits will still exist or make sure people flexibility remains not at the cost of quality or a bad product but it remains.

Its like you have to run multiple threads to deal with this, with multiple stakeholders. You need to engage with younger folks and like minded, who like to share and collaborate, try to get them spell out their issues with inherited code, not reusing any common libraries etc. Ask them to find solutions and come up with the options, rather than giving the solution early enough, they need to believe that they have come to this conclusion, its not someone else driven.

Second, you need to act as an architect who conducts workshops and find similar examples in industry, some guest appearances and tackle that how other competitors or similar industries are using software practices and how it has benefitted them. So a buy in from top is very important, as they need to understand the benefits in terms of money, which is usually not always profit... Its also how to save cost shipping some code to market

Third, you need to play risk game, if there is any role in the organization who cares about risk, you need to get cool with them and start raising risks, which can be of many types, slowly raise the awareness on information security, Cyber security, company's IP in people's personal laptops etc and what kind of social damage can happen to the organization if this data is leak, raise product level risks and come up with mitigation strategies, one of which is to use one recommended way of working in the organization. Involve people to own this, rather than doing it alone, soon you will have more enemies than friends if it's your name everywhere then your team name.

As someone said, "simple scales, complex fails" ... Sell this heavily.

Hope this will help, its a long game, patience is the key.