HI spilt_yogurt. Welcome to Geekhack.
Those Redragon boards seem to be great for the price.
You could try some quieter switches, or some that are not as high-pitched. I work in a school and have asked a lot of coworkers and students what they think of different clicky switches. None have minded relatively bassy switches like Alps SKCM or box jades, some are bothered by high-pitched switches like capacitive buckling spring or MX blues.
I imagine you've got some Outemu blues in your Redragon?
There are a lot of options for a quieter switch. There are dampened linears and tactiles, regular old linears and tactiles, and more exotic options like Topre (really fancy capacitive rubber domes, which are buttery smooth). It all depends on where your tastes develop. You may want to get a relatively comprehensive switch tester and play around with what's on it for a while before buying any switches in bulk. I
usually recommend this one since it has a ton of different switches for a reasonably good price, though a lot are duplicates in another guise, like RGB vs standard, etc.
There are tons of websites, even just regular old Aliexpress can be used for a whole build. It sort of depends on what you want, and at what price. I'm no expert on the LEGO stuff though.