Over here I have a Lenovo Yoga 500-something (it is a 2-in-1 model, just like you have). 6 screws are required to remove the bottom half of the laptop and that is it, full access to RAM, HD. Could hardly be any easier.
However, I do think that when a complete disassembly is required, the hardware is oriented more optimally for getting rid of generated heat when the device is in operation. Or at least less constricted by solid parts the block the natural rise of heat. The cooling fan inside your laptop should have to work less hard than then when hardware is oriented in my Lenovo.
Replacing the (original) HDD for a simple SATA model hard drive is the best thing you can do for your HP device. I did the same with my laptop and although it isn't a speed demon by any means, it is much more pleasant to work with. However, Windows 10 migration from Windows 8.1 (the original OS) made the laptop very slow after some 30 minutes of use. Only a browser with 2 or 3 tabs open and it became slow immediately. It also took between 48 and 72 hours before the battery was fully charged and regardless of this, the laptop screen would dim an get brighter whenever it thought it was charging/on battery. Which was even more irritating than the laptop not "waking up" properly after closing the lid.
Re-installed Windows 10 from scratch (using the method on the Microsoft site for installing Win 10), same problems. Very frustrated I figured I had nothing to lose to try Linux (ended up with: Pop_OS! from System76).
No more dimming, battery charged to 100% in a pretty short period, resulting in the screen not dimming every few seconds anymore, opened browser with 10+ tabs, while listening to internet radio, actively using VPN for remote working and opened document in the LibreOffice word processor. All without a hitch for any period of time. Laptop is "waking up" much more reliably than it ever did under Windows 10 too.
If you are not squeamish about Linux and you wish to give your HP device a second lease of life, it might be something to consider for you too. In a lot of ways the Gnome interface of Pop_OS! is a drastic improvement on the mess that Windows 10 can be (when you need to configure computer settings).
Sorry for repeating the Linux story from my laptop. Just thought I should mention it as an consideration.
If you want to expand your RAM, the manual states that 8 GByte is the maximum. So if you have 2 RAM slots, you can use 2 x 4 GByte RAM modules to get to 8 GByte. It is possible that the 4 GByte you currently have in that laptop are 2 x 2 GByte modules. In that case you will need to replace both of them. Maybe you are lucky if you can get rid of your old RAM modules, but don't expect to get much for them.
But you might be fortunate and have only 1 RAM slot occupied with a 4 GByte RAM module. You could gamble and buy another 4 GByte RAM module. Pay very good attention to the type of RAM you are buying, else you'll end up with the wrong type. RAM modules that use DDR 3 technology come in two types. If you'll get the wrong type, your laptop won't boot.
Even if you get the correct type, there might still be the possibility that both RAM modules are incompatible in combination with each other, while working just fine separately. Best way to go get a new set of 2 x 4 GByte RAM modules (same brand/make/model) of the correct type and Windows 10 will perform quite a lot better. Your old single 4 GByte RAM module is much easier to flip and for a higher price too.
Still, while you will notice the effect of increased RAM capacity in your laptop, it pales in comparison with exchanging the standard HDD with an SSD. That is an order of magnitude more noticeable. Depending on the storage capacity of the SSD, it is cheaper too. The price difference allows you to buy an empty external HDD enclosure and you can build your current HDD into that enclosure. You haven't lost any data this way, you have sped up your device considerably and you gained an external drive with storage capacity you were already used to. Hook that external drive up to one of your USB 3.0 ports and it will be faster than whatever SD card you wish to use and you won't be bothered by that 32 GB limit.