And if so, would it then just be a matter of time and effort (rather than equipment and materials cost) to do a more thorough sequencing of your own DNA than any lab would ever be willing to do for you?
https://aseq.substack.com/p/bringing-up-an-old-ebay-miseq
Your issues are that you will still need to purchase reagents from the sequencing instrument vendor. They will try and push you toward a service contract.
Each kit will cost ~$600 (cheapest kit) an old Illumina sequencer which you can still buy reagents for will cost at least $5000.
Doing a whole genome this way would be expensive… I’d guess $10K to $20K perhaps? You’d need a lot of kits… or one of the high spec sequencers (NextSeq 550 etc).
Alternatively you could look at getting a nanopore sequencer. This will be cheap but the data quality is different (and may not be comparable/require high coverage for certain applications). I’d guess you could do a (30x) whole genome for <$10K all inc here?
Principally create new flowcells coated with an oligo lawn would be difficult. Not impossible… but a non-trivial project…