Eltoo whitepaper can be found here:
@SomsenRuben did the work on both Blind Statechains and Spacechains, here are his presentations on both:
There's still plenty of work to be done - the checklist on https://anyprevout.xyz lays out the steps to BIP 118 activation - but the last PR at least is fairly lightweight in terms of LoC to review. Dig into it at https://github.com/bitcoin/bitcoin/compare/master...ajtowns:202101-anyprevout !
Bitcoin Maston Instance