On a positive note, Belarus and Serbia have confirmed!
So that just leaves:
Albania
Armenia
Malta
North Macedonia
Portugal
Not sure whether BBC would take part in JESC, previously they avoided having young children involved with phone votes (such as in the Oliver! casting programme in 2008, where the public could only vote for who would play Nancy, with the kids chosen to play Oliver selected by the judges). Since then they have allowed children to compete in The Greatest Dancer, which had phone voting, so there may have been a policy change on this. Not sure if the BBC represented the UK, and made a success of it, if that would block S4C from ever returning for Wales, if BBC got the UK wide rights. I could see them showing it on CBBC, seems unlikely they would show it on BBC1. In recent years, the BBC has largely only competed in Spin off events they were hosting (EDC 2007 & 2008, Greatest Hits 2015, EYM 2018), with the sole exceptions being EYM 2010, and broadcasting Europe Shine A Light this year.