Note: To install all extensions by default, you need to add a config value with the extensions you want to install upon startup (you can also do it manually in the menu though). Here is the config entry that installs *all* extensions upon startup (this might *not* be what you actually want!).
LNBITS_EXTENSIONS_DEFAULT_INSTALL="watchonly,satspay,streamalert,tipjar,lnticket,invoices,boltcards,paywall,subdomains,discordbot,bleskomat,jukebox,splitpayments,withdraw,example,tpos,smtp,livestream,ngrok,events,lndhub,lnurlpayout,diagonalley,copilot,lnurlpos,deezy,lnaddress,satsdice,offlineshop,lnurlp,usermanager,cashu,nostrnip5,gerty,scrub,hivemind,boltz,market,lnurldevice"