I have used 2hp modules before. I still have the Mix. Frankly, though, for this amount of money, I would say to not put a bunch of them in. They wiggle even if they're built rock solid, amd the knobs are not fun. If you decide later you need some function they provide and have to have it in 2hp, then go for it.
2hp Hat - You can probably skip this. You have noise in your setup. Patch the noise to a VCA/low pass gate/filter and ping the CV input/send it short envelopes. This is also sort of my advice about the Queen of Pentacles. If you try it and like it, then go with it (the filter and effects alone might bw able to help the modulation problem and give it some life). Whether you like the Queen of Pentacles or not, however, modular presents a great opportunity to synthesize unique percussion using the exact same tools you make synths with, as well as an opportunity to blur the lines between melody and percussion. The more you play with this system, the further away you'll get from assigning things standard roles like "drum/bass/lead".
2hp Euclid: Pam's has you covered here, I think. Plus the Oxi One.
2hp Arp: Another one where your sequencing hardware has you covered, but you've also got those quantizers to turn any modulation into an arp. A quantizer is almost always better for in-rack than an arpeggiator.
2hp TM: If you can make room for it I would 100% recommend the After Later Audio Alan instead.
Once you have a Rample and a 2hp Play, I can't help but think you should just try a Bitbox or a Squid Salmple - especially if you're also worried about the Queen of Pentacles and the SD card on the back. Maybe that's just me. Vocal one shots and all that can also be a 505 thing, but I'll leave that up to you. You can also look into CV to MIDI converters like the Befaco CV Thing or the Sweet 16 faderbank (a great multi-function module in general, albeit a big one) to allow you to send modular signals to non-modular gear like samplers and control their MIDI ccs for that modular sampling vibe. Sampling in Eurorack can be great, but this process will definitely help you decide what you want to do in rack or out of rack and where each task suits your needs, and you may find one of these options more suitable. I wanted to make a Eurorack sampler for a long time until I thought about it and realized that my Polyend Tracker and SP404 would let me put a sample anywhere I wanted in most ways I would want, and that unique but purposeful sample placement was easier to do there anyway.
The 2hp Pluck is admittedly hard to replace this way. There's always Rings or the QuBit Surface, but those are definitely bigger. People do like the Pluck.
There is one kind of 2hp module that I always suggest to people: passive low pass gates. I have the Takaab and Meng Qi brand ones and they are great for setting up quick and simple percussion out of any sound you throw at them, or just having extra signal paths for your oscillators that give them a unique character.
Overall, this seems pretty balanced. Usually imagined systems this big are a bit of a mess. More modulation is nice, so if you expand, definitely look there first.