I will get the ball rolling with sharing the first link to good HFY themed content. The below is a story narrated in youtube videos with really good graphics (Created using the game Stellaris)

Stellaris Invicta 1 - Greater Terran Union

In 2200, mankind has journeyed to the stars to seek vengeance on their old enemy and extend their power across the galaxy.

1. Prologue
2. Part 1
3. Part 2
4. Part 3
5. Part 4
6. Part 5
7. Part 6
8. Part 7
9. Part 8
10. Part 9
11. Epilogue

Retreat, Hell by Ilithi Dragon, an ongoing military Isekai story following the story of a army platoon fighting genocidal fantasy elves. If you want very well written war porn - here you get it. Author doesn't updates his wiki too often so us UpdateBot.

https://www.reddit.com/r/HFY/wiki/series/retreat_hell/

One of the greatest HFY stories ever written The Deathworlders by Philip R. Johnson, AKA HamboneHFY.

https://deathworlders.com/

Seven Days of Fire, another very well written campaign against alien fantasy races. Series is complete. https://www.reddit.com/r/HFY/comments/br65hz/oc_seven_days_of_fire_prologue/

Yes! This was my favorite community back on reddit and it's also here. Now I can finally feel at home here on Lemmy :') hello

The Last Precursor

On royal road: https://www.royalroad.com/fiction/54732/cryoverse-the-last-precursor-completed

A completed story of 97 chapters about the last human alive in the universe.

Humans are the urban fae

www.tablesfrombeyond.com

The Last Question - Isaac Asimov

Isaac Asimov: This is by far my favorite story of all those I have written. After all, I undertook to tell several trillion years of human history in the space of a short story and I leave it to you as to how well I succeeded. I also undertook another task, but I won't tell you what that was lest l spoil the story for you. It is a curious fact that innumerable readers have asked me if I wrote this story. They seem never to remember the title of the story or (for sure) the author, except for the vague thought it might be me. But, of course, they never forget the story itself especially the ending. The idea seems to drown out everything -- and I'm satisfied that it should.

Available as an audio-book on archive.org, narrated by Leonard Nimoy

Or

Book format: The Best of Isaac Asimov archive.org Requires a free account to "check out" books from their digital library.

Humans are Space Bees and an archive.org backup because tumblr links are notoriously breakable

second try at sending over Humans are the Urban Fae and an archive.org backup, again because tumblr links are notoriously breakable.

Last Contact and an archive.org backup because tumblr

A nice combination of Light Fantasy, Dark Scifi and good story writing. Author is very communicative and seems to have a solid release schedule.

Elves and Battlecruisers

Predator and Prey

The scourge of the galaxy, the Joltul'ra, devour everything in their path.

Story by visser9466

https://www.wattpad.com/story/64166046-predator-and-prey