Voice call implementation in Gajim is only waiting for an upstream improvement, it is already working otherwise. Sadly upstream seems slow in fixing this.
You can try this unofficial Windows version of Dino though, which supports calls: https://github.com/mxlgv/dino
Edit: and there is of course always Movim, which works fine in most browsers and supports 1:1 calls.
XMPP clients for Android are great, for iOS a bit less so. On Windows / Linux Gajim is probably the best option right now. JoinJabber.org has a good list of up to date clients (do not use Pidgin, it's horrible and super outdated).
In general the main downside compared to Discord is the lack of voice-channels. 1:1 voice or video calls work great with the Android clients and group calls are partially supported in some desktop clients (that is currently very active field of development for XMPP clients).
Why wouldn't XMPP work? It fulfills all your requirements and has nice modern apps, especially for mobile. Definitely better than Matrix.
The easiest to get started with it would be setting up a Snikket server (Prosody based, but pre-configured for small private groups).
If you connect via 10gbit PCIe extension cards it is often a question of how many PCIe channels the CPU has and if the mainboard you are using has these connected directly to the CPU or needs to pass them through the mainboard chipset which is much slower.
There are external GPU cases that might work with your laptop, but at least on older models these were relatively bandwidth limited which doesn't matter that much for gaming, but I guess it might cause more problems with AI workloads? On the other hand, maybe not if the model fits completely into the vRAM of the m40?
SimpleX is not suitable for larger group chats.
XMPP has a few quite popular privacy related public channels: https://search.jabber.network/search?q=privacy
(For those unaware: xmpp participant counts are actively connected users, not like Matrix or Discord that counts who ever joined the room years ago and never came back).
You can always encrypt the backups you upload there.
Depending on the specs of the shared webspace it is possible to install some php based webdav software to easily sync files with it. KaraDAV for example.
I wonder if their recent bid to take over Intel, is related.
The irony would be very thik as Qualcomm played a big role in killing Intel's 2010er efforts to enter the mobile sector.
Any pc with two network ports and Ipfire will do. Easy to set up and configure.
Glinet makes travel routers with OpenWrt on them and internal microSD slots as well as external USB ports. Pretty easy to turn those into a media server as well.
The audio is very quiet, it's probably a microphone or post processing issue.
Castropod is cool, maybe you can try to figure out why it doesn't properly federate with Lemmy and file some issues on both sides?
They probably used on of these federation "helper" scripts that just siphons up the entire fediverse. That is just a bad idea and results in a bloated database like they were complaining about.