The question is:
Is there a way to write presets somewhere in a disc and copy them to another computer or just store them for the further use when I decide to reinstall my operational system?
For LV2-plugins there's a folder - /home/username/.lv2/. If to copy this folder from one linux system to another - it works well (at least with GX plugs, verified).
For lxvst-plugins there's a folder - /home/username/.config/ardour5/presets/. Also works well, if to copy it somewhere and use (verified with Noize Mak3r synth).