That is a rather different question than the outset but hey. Most fun with sequenced audio these days is software mixed on the PC side of things so sound card concerns only really come into that when you want fun midi and microphone/line inputs via them and whatever concerns you have for the general quality of the DAC and such when it comes to the signal going out. That said if you kick it to hardware to mix I could certainly see a weak internal driver tank things similar to how many modern graphics cards have weak support for older formats and approaches full of bugs. Also there is more to limitations than just CPU speed -- number of cores (assuming the program can even handle it), memory, hard drive (less a problem for most audio, can be a massive problem for video if you have to try to load 16 4k streams all at once).
SD cards. That is fine if that is your workflow* and we can do things but it needed to be asked as it gets more specialist. If you get one of the cheapo USB adapters with full size SD (possibly one on each side) and microSD (and time was miniSD) then chances are there will only be the one internal handler for SD such that you can only have one in at a time. More exotic ones do exist with multiple pathways (though most will be two only), and if you are willing to make it yourself then 3 SD slots fit easily in a front panel/drive bay slot. Modern USB 3.0 ones if you have a header spare on the motherboard will probably also be able to put those three on an internal hub without suffering speed** or power issues and not see you need an excessive amount of headers on your motherboard used for this.
https://www.asus.com/motherboards-components/motherboards/prime/prime-z590-a/techspec/
*some might want the slots but are happy to lightly pull one or two cards out if they need another slot to say dump from a camera a few times a week. Multiple devices all the time/potentially needed at a moment's notice is a normal enough workflow as well.
**I say that but looking at
https://www.bhphotovideo.com/c/buy/Memory-Cards/ci/1097/N/4093113320 then some SD cards are quite fast indeed such that even full on USB3.2 might be troubled in the ideal scenario. USB 2.0 getting maybe 35 megabytes a second on a good day, usually more in the high 20s. Not so bad for loading up your phone SD card with a few podcasts but if you are transferring gigs and gigs of video, wave audio capture or raw photos that gets tedious.
You can also add ports via PCI express, and some of those could probably run extensions (either around the board or maybe through it), and if really fun could play with a soldering iron to make them internal. That said this motherboard looks like it only has the one slot for this which will probably be taken by a graphics card if you go that way, or a fancy sound card (assuming you don't go for a USB one).
On microphones then I would ask where you are heading. Many modern ones (especially those aimed at podcasters, streamers and the like) will be USB and quite nice for it, most sound cards mic ports being 3.5mm and barely powered. If you are heading into even the semi professional world you will want something resembling proper XLR audio inputs which gets easier to set up at this stage while you are building out. 3.5mm mic ports these days being useful for headsets to speak your grandma on skype rather than anything real.
Some will also go the other way and put everything through a standalone mixer (pro tip there is buy standalone audio recorder that auto records everything while the mixer is powered on) and have the PC do whatever it needs to with it almost as a secondary concern.
We also have not talked about latency in this either -- USB (and especially bluetooth) potentially getting up there for it. Not so bad when laying down individual tracks, or commenting on a game/news of the day, potentially killer if you have a live band in the studio as it were or trying to play along with backing tracks or having a monitor speaker/headphones, and also stuff going out live to go along with something.
"headphone port of my screen"
? This potentially something else again if the screen is HDMI and you are taking audio from that rather than using the internal analogue audio options of the motherboard.
It sounds like you have just been thrust into the world of PC driven music production, have encountered the limits of the basic PC motherboard and are now amazed by the potential options for everything. Wonderful thing to experience but unless you are going to pay big boy money you are probably best advised to figure out what direction you want to head in. It sounds like sequenced audio and personal/instrument at a time for later production is where you are heading (as opposed to live audio, guest heavy podcasts, performance, full band capture). In engineering parlance this would be get a specification for what you want and it applies to most things -- websites, graphics design, car tuning, personal trainers... all will have stories of people that wander in mostly just wanting things to be cool and capable without a tangible end result to aim for and it being a nightmare project. Don't do it to yourself.
At the same time while "buy once, cry once" is a philosophy that works then in audio you can afford to take it a bit more easy, buy something, hit its limits and then sell it on to change up for something more, there is also the middle ground of buy something cheap and if you break it/hit its limits immediately buy something nice for that.
