only the open finance part of the application uses Alby and we are looking into LNBits, since we'll need a reliable API to get transaction lists from.
The rest of the application only needs an LNUrl & a receive btc address to function, so you can use your self-hosted payment gateways in this rudimentary implementation way. this does leave order verification to be a manual process that services like BTCPay & LNBits fill, so integrations for those are definitely part of the long term goal.
For fiat integration we've settled on hopefully finding a good provider that does a crypto onramp integration at the end of this all everything should solely function on btc.
For SEO we rely on build in content packages that allow you to specify all meta data in the top of the page, a bit barebones implemented today but we hit great lighthouse scores on the demo builds.
Super thanks for the feedback!