Considering you already have a very functional and recent Mac, I'd suggest waiting up to 6 months for the possible M2 model, unless you can get the M1 model for cheap. It sounds like your 2020 MBP is fast enough, albeit loud. For memory, 8 GB is fine for a lot of people, but in your shoes I'd recommend 16 GB given your software choices. (There is likely no need for the 24 GB RAM option that would be available with the M2 model.) One big added advantage to waiting is that the M2 model will be supported for much longer, as the M1 iMac is only half a year newer than your MacBook Pro, since the M1 came out in 2020 too. That was my plan too for a Mac mini, but in my case I found the M1 for cheap last year in the configuration I wanted, so I bought it.
Don't bother with a trackpad unless you need/want one. I personally dislike using trackpads with desktops. Apple's mouse isn't the greatest but if you don't like it, you can get one of many other mice. I often prefer wireless RF mice since no Bluetooth pairing is required, but there are many decent third party Bluetooth options available too.
As for storage, it is hard for us to know how much you need based on your post. 256 GB is sufficient for many people as a minimum, but 512 GB is often preferred. For example, my kids and wife all have 256 GB in their Macs and it works well for them, and I am fine with 256 GB with my MacBook too, but I have 1 TB in my Mac mini although truthfully I probably only need 512 GB for the main drive. Fortunately, since it's a desktop, it's also easy to expand the storage later with external USB-C drives. As mentioned, I have a 1 TB M1 Mac mini, but have expanded that to 4 TB with two external SSDs, 2 TB and 1 TB in size. I have also added a 4 TB hard drive for Time Machine, so my Mac mini currently has a total of 8 TB. Some of these drives (and my monitor) are running through an inexpensive
4-port Thunderbolt 4 hub.