I have a Framework laptop 13" (12th generation Intel), which works quite well and would fit all of the above points, mainly upgradability. Framework tests their laptop with Linux (specifically, Ubuntu and Fedora) and has a user forum. They do ship to Europe, and their marketplace has refurbished options if that interests you.
You can set a battery charge limit in the BIOS/EFI to reduce the impact of the battery being constantly at “100%”. I have set mine to 75% and it works well, giving me around 5-7 hours of battery life.
For viewing 3D models in a virtual machine, I think you need a second GPU, so the Framework laptop 13" may not be as adapted, as it only has integrated graphics. They also have the laptop 16" which has discreet graphics, but I’ve heard mixed things about build quality and battery life. It is also way bigger.
Practically any new laptop costing more than €900 will meet those requirements. I think it would make sense to add additional requirements to narrow things down. Screen resolution, refresh rate, and color fidelity will be quite different across models, as will be keyboard layouts.
I’ve always bought Thinkpads. Linux support is great with them and Lenovo is pretty good with working with LVFS so BIOS and firmware updates don’t require you to make USB boot sticks and update through the UEFI/BIOS. It’s just a case of running fwupdmgr and rebooting.
Boutique Linux laptop resellers resell Clevos, Tongfang, Bmorn and a few other Chinese/Taiwanese laptop brands that don’t work as well with BIOS and firmware updates. Sometimes they’ll also slap Coreboot on them. They’re also ridiculously expensive considering their overall build quality and compared to the companies that resell them as just plain Windows laptops, where you can order them without an OS.
Take for instance the TUXEDO InfinityBook Pro 14 - Gen9 - INTEL. That’s actually a Tongfang GX4MRXL and Tuxedo is selling it for 1091,60 euro. That’s £924 in the UK. I can buy the same laptop in the UK from PC Specialist and the price including tax starts at £741. When you remove the operating system (Windows) from the selection, the price starts at £655 including tax, allowing you to put the money saved into a better CPU, or more RAM/storage. And if other Linux boutiques are running Linux on it, you can be sure that Linux will run on that too.
For your needs I would look at the Thinkpad P series. As for needing to upgrade components in the future, I just buy the laptop with what I’ll need for the forseeable future and forget about it. Like my current Thinkpad has a 1TB SSD and 32GB of RAM and I’ll never use all that. But when speccing it out, I added it because it totalled less than the budget I’d allocated myself for a new laptop. The only thing I wish I hadn’t added was the 4k screen. It eats the battery life, but boy does KDE look great on it.
Lenovo Yoga Slim 7 Pro X (14ARH7) - daily relaxed driver. No complaints whatsoever - signal video calls work great, Google Meet video quality was kinda grey but generally good. It was running Windows where I used WSL a bunch up until I recently replaced it with Aurora. Not great for intensive applications despite the Nvidia GPU. I bought mine used on ebay
Thinkpad T480 - bit of a junker as it was released 2018 - use to test stuff with, but it can actually do relaxed browsing and it’s what I’m using right now running Universal Blue Aurora. Two batteries - one is hot swappable - so I loaded a bigger one bought on Amazon. Historically touchpad was terrible on Linux so I tended to keep Windows on it unless I was testing a distro. But when I loaded Aurora on it a few weeks back, the touchpad was fine - maybe libinput quirks were figured out, or the kernel is better.
Framework Laptop 16 (AMD Ryzen™ 7040 Series) - I was very disappointed with the touchpad experience when I loaded Linux (forgot which distro) on this a while back. It’s currently running Windows and I’m not using it too much, but plan to install Aurora on it soon. Finger crossed the touchpad is good with Aurora.
Kubuntu KFocus Ir14 GEN 2 - most recent purchase last month. I see this as my goto for the long-run, especially for intensive programming, as they do actual quality assurance on the hardware + KDE desktop. I haven’t spent a ton of time using it yet. Not sure if I’ll replace the Kubuntu which they test and warrant with Aurora.
Dell Latitude 9440 14" - this is more of an example of what not to buy, as it runs Windows for hardware reasons. I bought it more for a family member to use a “PC” instead of a Macbook - touchpad was unusable on Aurora so I put Windows back on it. One reason I bought it is that I was curious about the feel of Dell’s “haptic” touchpad, but haven’t really been able to understand the difference.
Work is mostly Windows / Mac so it’s handy for me to have hardware running that (the Dell above + an old Macbook Pro) for ease of reference personally.
I like the idea of using old cheap hardware like my Thinkpad T480 for simple downtime tasks and whatnot, but every so often I do notice the lag so may not run it into the ground.