Want to upgrade my PC

Definitely get an SSD. Upgrading my laptop from an HDD to just a SATA SSD gave me much faster boot times and app load times. Even some faster NVMe SSDs are cheaper than SATA SSDs now (around INR 5800).
But a thing to note, M.2 SSDs use either the SATA connector or PCIe lanes and the faster ones are the PCIe ones. M.2 SATA SSDs are not compatible with PCIe slots and vice versa, be careful while buying. For some weird reason, both are of similar cost on Amazon India.
Another thing, your CPU and motherboard have only 16 PCIe lanes all of which are used by the GPU. Using a PCIe SSD with your CPU will cause them to share the PCIe lanes and potentially reduce the performance of the GPU (though not by much). You can either buy a motherboard with one PCIe x8 and two x4 where you use x8 for the GPU and x4 for your SSDs (I think this is the best since you don't use your GPU much) or go with a new CPU with 20 usable PCIe gen 4 lanes and a compatible motherboard.

IMO get Crucial MX500 1TB SATA SSD. Might be enough for you.

Unless you are using PS & LR heavily, I doubt you are getting CPU bottlenecked. Might hit RAM limit earlier than CPU limit. Check this.

If you have made up your mind on upgrading, i5 12400 (17k) + B660M mobo (12k) + 16GB RAM 3600MHz (5k) might cost ~35k. Sadly I don't see Gigabyte B660M DS3H for 10k these days, about 12k now. MSI B660M A Pro is under 14k & a better mobo VRM wise.

If you are fine w/o iGPU, i5 12400F is usually 14k or so, under 12k on FK (but risky).

Agree with @OMEGA44-XT. Get a 1 TB SATA SSD. Read speeds are slower than NVMe, but won't make a huge real world difference for photo editing. I have used the same PC with both SATA amd MVMe SSDs and the difference is really small.

Apart from that, adding another 16 GB RAM stick might work well as these processes are RAM intensive. Your motherboard supports 2666 MHz RAM. Getting 2666 MHz would be better as 2133 will have poor resale value despite their long working lives. You should be able to find something in the market section here.

If it's just for photo editing and not for gaming, just try upgrading to a good sata SSD (preferably one with DRAM like mx500 samsung EVOs etc) and dual channel RAM (You can however hold on RAM until you test out an SSD)

Since you are on HDD the change will be mindblowing. If you are still not satisfied then you can think about upgrading the rest of the system. You investment on SSD would still be safe.

If you have some space left over on your boot SSD, you could also partition that away and try using it as cache for your HDD. I've heard you can do this with either Intel RST or Windows Storage Spaces, but they're apparently poorly documented and/or finicky, and I also don't know if they support using a partition on a drive rather than the whole drive. PrimoCache is a third party paid software for exactly this use case, and from what I can tell it does support using a partition as the cache, and they have a 30 day free trial, so you can test the solution for no cost. If it ends up being good for you, a license of the software (about $30) is significantly cheaper than any of the other options being discussed, while keeping your bulk storage and workflow unchanged.

Mind you, the easier option is still new hardware (as everyone has been suggesting), but this could potentially allow you to scale your storage more cost-effectively if you end up needing more storage on your workstation (though at that point, you should probably look into a dedicated NAS). Either way, costs nothing to try.

My suggestion would be similar, or to max out speed you can use 2 SSDs in RAID 0.
And while you are at it, you can add another 16 GB stick, which should help since these qre memory intensive programs. The CPU is good enough to handle the load.
Replacing HDD with SSD will provide good boost, and it speeds up things

You can go with following.

• CPU - 12400F (from fk, its open box delivery, its sold for 12k on some occasions).
• Mobo - ASUS Prime H610M-E D4 (7.5k).
• RAM - 3200 Mhz (8gbx2) - (4.6k).
• SSD - MX500 (7k).

Total - ~31k.

The cheapest and fastest option is to get something like this PCIe NVMe adapter that goes into a slot below your GPU. Then you'll be able to use any NVMe drive.

Your mobo might let you boot from it since it's a relatively recent generation. For my 3rd gen mobo I had to modify and flash a custom BIOS. At the very least you will be able to use it as a super fast secondary drive. It is plug & play.