Here are the pieces I used often in church:
Floriano Arresti Elevazione for prelude, Ricercar for postlude
IMSLP28277-PMLP58193-Arresti_Ricercare_Organo
IMSLP28278-PMLP62146-Arresti_Elevazione_Organo
Pastorales for Christmastime:
Zipoli
Pasquini
Frescobaldi
Scarlatti (Domenico)
and many others
Domenico Zipoli Offertorio, Elevazione and others
Sonatas by Scarlatti for organ or harpsichord. A few are specified for organ
Vivaldi/Bach 16 Concertos not all by Vivaldi, others by Marcello
Any other concertos from the high baroque by Torelli, Corelli, Geminiani, etc. arranged for organ
Vivaldi: 4 Seasons, especially Spring. Use piano arrangement or organ arrangement found on IMSLP:
https://s9.imslp.org/files/imglnks/usim ... llegro.pdf
https://imslp.org/wiki/Violin_Concerto_ ... i,_Antonio)
I also played the Toccatas of Michelangelo Rossi especially no. 7. Like Frescobaldi but slightly more modern.
You can also play transcriptions of vocal works. The sky is the limit!
Enjoy!
RS