Fungus is very much alive and to meet peoples caloric requirements means massacring hundreds of trillions of them. We just can't easily hear them scream. They communicate with one another over massive fungal networks in forests and jungles. Fungus are fascinating. They can recognize patterns and make decisions. Slime mold is even more interesting in that it can remember complex patterns, solve mapping challenges and make decisions without a nervous system suggesting our understanding of the term life is likely very incomplete. Slime mold can remember feeding times and locations.
We're only massacring the fruiting bodies. The mycelium is just fine and lives on to create even more fruiting bodies. It's like picking apples from an apple tree. The tree itself isn't harmed in the slightest. The only difference is that many fruits are designed to be eaten so that the seeds can pass an germinate, whereas mushrooms achieve this through spore release.
For some of these fungal meat-substitute products, I think you do eat the mycelia (for bystanders, the fruiting body we eat is mushrooms). But I don't think the fungus is bothered about it the same way the chicken is.
I feel like this might have been shown in the 2019 documentary 'Fantastic Fungi' (https://www.imdb.com/title/tt8258074/) - really interesting and fun movie.
