Yes, use (Peace) Equalizer APO if you're on Windows 10 PC.

But ya, the Qudelix 5K is the ultimate device right now to pair with headphones/IEMs as it has parametric EQ (you won't really be able to find parametric EQ with Apple phones/devices) and other extra features in its app. It's normally $110 on Amazon USA (Amazon USA ships to some other international countries like those in Europe) but it's often out of stock these days and so it's $130 from the Qudelix website, international express shipping (be aware of extra courier (express shipping companies) processing/handlings fees, maybe add another ~$20+) from Korea. Sometimes it restocks on Amazon, so check it out there from time to time, try to make a price/in-stock alert for it.

The Qudelix 5K will be really good with Apple/etc. stuff as they often don't have access to easy parametric EQ.

As in theory any device you pair the Qudelix 5K with will apply that parametric EQ. So that includes Xbox, PlayStation, Nintendo Switch, and other video game consoles, TV, tablets, et cetera.

See this recent thread for the Qudelix 5K's features: https://www.reddit.com/r/HeadphoneAdvice/comments/vo8dua/what_are_the_main_differences_between_the_qudelix/

Somebody recently did stickers/etc. for the Qudelix 5K if you want to remember the button functions: https://www.reddit.com/r/headphones/comments/v627gl/qudelix_5k_sticker_final_design_with_file/

For the Qudelix 5K, there's also a new FW 2.0 coming probably this end of November or year: https://www.reddit.com/r/headphones/comments/yqbe0z/qudelix_5k_fw_20_update_coming_late_november/. It will have more parametric EQ customizability, so you can now better EQ one side or the other for any channel or hearing imbalances and so on.

This is the main Qudelix 5K thread (on Head-Fi): https://www.head-fi.org/threads/the-qudelix-5k-thread.914628/page-243. Don't forget to check the official Qudelix forums though it's not as active as other more generalist audio forums.

For IEMs specifically, try using Spinfits in different sizes. They have a rotation gimmick that may help with that.

Especially the Spinfit W1, I liked that one for fixing channel imbalance from IEMs (usually it's louder on the left side if the IEM/headphone is the problem, for your ears, it'll depend on your hearing imbalance and how it perceives the other issues). This ear tip (and many medical grade silicone ear tips) does lower/alter the bass quite a bit though, so it's up to you.

The new FiiO HS18 is oddly enough really good with fixing that channel imbalance too. But the problem with that one is that Small and Medium size can be quite a big difference due to its shape (think trapezoid). So basically it tapers off or like flares right and so you might need a size between Small and Medium or say Medium and Large. For now there's only those three sizes, so you'll either have to shove deep one side or shallow fit the other side and so on.

Same with Final Audio E ear tips. It's probably like the length/height of the ear tip. Or like the umbrella shape (especially if it's more of a triangle, cone, trapezoid, etc.). Like a similar situation happens with Spinfit CP155 and CP145, as in you just wiggle it a bit and you can fix some of that channel and hearing imbalance.

Here's a bit more info on ear tips: https://www.reddit.com/r/HeadphoneAdvice/comments/z0d7br/need_advice_for_purchacing_tips_for_my_pair_of/ix63xfz/ and https://www.reddit.com/r/HeadphoneAdvice/comments/z0gqhb/iem_tips_recommendations_for_someone_who_hates/ix60a53/ and https://www.reddit.com/r/headphones/comments/xixh4y/iems_never_work_for_me/ip9gwan/

Here's the reviews of someone with a lot of ear tips: https://www.audioreviews.org/guide-to-iem-silicone-eartips/

Here's the ultimate ear tip thread: https://www.head-fi.org/threads/best-iem-tips.626895/page-146

This is how you should use Etymotics or really any IEM or TWS earbud to make sure you have that good/perfect fit for that vacuum seal (necessary for the bass to be properly produced): https://www.youtube.com/watch?v=8KwXEqe6Gq4

For headphones, try aftermarket earpads from Dekoni, Brainwavz, etc. Maybe the angled versions will work if you shift them in different positions. It's been so long since I've used my Brainwavz/etc. earpads though so I can't really confirm that.

Otherwise, research more about allergy medicine (antihistamines/etc.) and how they can clear your ears (there's things like Eustachian Tube Dysfunction, etc.). Sometimes it's placebo for hearing loss, tinnitus, etc. but it can help a lot when you have blocked sinuses, so kinda worth it anyway.

But ya, just talk to your medical doctor first. Usually visits/tests/etc. with ENTs and audiologists are covered fully or partially by local/state/national/etc. governments, especially if under or over certain ages, and so that can help you figure out any remedies for the problem.

Though yes for the most part it's just learning to live with the hearing loss as there's no cure for now. Visit /r/tinnitusresearch and so on for hope though as it seems this upcoming decade we'll finally have actual products for general consumers, might be say 2025 or so though.