Reliable vote counts are not hard. Back in the mid to late 90s we took standardized school tests by filling multiple choice bubbles on a Scantron sheet. Those sheets were fed into a machine and tabulated. I feel like some version of that tech is the most reliable and provides a secured paper backup.
Voter shows up at precinct.
Poll worker verifies voter is registered, name/address, ID if required etc.
Worker affixes a label with registered voter's unique ID number/barcode to a ballot (no personal identifiable info.)
Voter takes ballot to a privacy screened area to fill out the bubbles next to each candidate/question. If voter screws up the ballot, they get a new ballot and worker affixes a backup label.
Voter takes completed ballot to a machine and drops it for scanning. Ballot is read electronically, image is stored electronically for backup, and the paper is secured under lock in machine bin.
Machine tabulates the ballot and marks off registered voter as "voted".
If machine reads 2 bubbles for one office/question, ballot is flagged. If machine cannot read a bubble or scans missing questions, ballot is flagged. If voter's barcode label isn't read or missing, ballot is flagged.
All flagged ballots are reviewed daily or weekly prior to election night for early voting. On election night, flagged ballots are reviewed after polls close (both electronically and paper if necessary.) Anything that can't be matched back to a registered voter is discarded. Anything that's incomplete is only counted for the properly completed questions. Best effort made to determine which answer if a bubble is smudged/crossed out and another filled in. Corrected ballots are scanned and paper records still kept, along with record of authorized person who modified/certified the ballot.
All firmware and software used in this process must be hardened and secured to modern industry standards/platforms and all source code must be open to 3rd party validation/inspection.