Do we have any chance left of using software for our work without Big Tech behind it?
Yes. Pay for software from independent developers and small businesses. The entire reason big tech is where it is is because nobody wants to pay for software, and big tech is the way to make money off of "free" software. Software developers need money to eat, so this is the inevitable result of demanding everything for free. Actions meet consequences.
I pay for independent software, point is, only big money can afford to hire employees to work on free software, because they don’t make money from selling software but from being a monopoly. Free software will always win, which is not a bad thing of itself, but it also means that Big Tech control over the software world is inevitable.
The entire free software ethos indirectly opened the door to the Big Tech monopoly. There is no FAANG without open source, there is no open source without FAANG.