sudo apt install printer-driver-all should install all of the printer drivers in the repo. If your printer still doesn't work then Trisquel doesn't have the necessary driver, possibly because no free driver exists.
If you do end up buying a new printer, take a look at h-node https://h-node.org/printers/catalogue/en as the printers catalogued there should all work with free software. If you find that your printer works after all, I suggest adding it to h-node.
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