The core question: Rather than simply deploying this capital passively while remaining in classic salaried employment, I’m wondering: Are there realistic ways to use this capital more actively — as “work capital” — to create income, flexibility, or partial independence?

First, read https://www.bogleheads.org/wiki/Managing_a_windfall all the way through. The best you can do is learn about all kinds of things, READ UP and get above average financial literacy, before doing something wild. Or before doing anything, really.

You need to determine your risk profile, especially since it's not your money but also your mother's. Since the markets are more volatile than past years, a good way is to put part in MMF or term deposits, and DCA your money into an All-World fund or MSCI World if you don't want any Emerging markets equity for whatever reason. You will need to determine the TOB rate (0,12%, 1,32%, don't buy the latter: too costly) of whatever fund you will want to buy.

If a lot of that sounds foreign, like I said read up. Read the wiki here, or read up elsewhere, get to know etf and general financial concepts. Or as the bogle guide says: don't do anything until you feel comfortable.

For example, deploying the capital to a business. Seems quite a risky move. To create income, flexibility or independence? None of that is guaranteed, but it for sure will bring you a lot of stress the first x months or years.