thanks for the replies…
I think the point I struggled with is that in the Eastern Canon Law, it doesn’t specify that it can be at any church/rite that is Catholic, like it does in the Latin Canon Law. It just says “Divine Liturgy”. So what if it’s the Mass, not Divine Liturgy?

kind of confusing to think about…
According to Rev. Fathers Dimitrios Salacas and Krzysztof Nitkiewicz (undersecretary of the Congregation for the Eastern Churches), in Rapporti Interecclesiali tra Cattolici Orientali e Latini, Pontificio Instituto Orientale, 2007, the Latin code includes a number of canons that directly bind Eastern Catholics, which includes the 1983 CIC 1248 §1:Can. 1248 §1. A person who assists at a Mass celebrated anywhere in a Catholic rite either on the feast day itself or in the evening of the preceding day satisfies the obligation of participating in the Mass.
Also we have been instructed that the obligation is celebration of the Eucharist.
1993 DIRECTORY FOR THE APPLICATION OF PRINCIPLES AND NORMS ON ECUMENISM:115. Since the celebration of the Eucharist on the Lord’s Day is the foundation and centre of the whole liturgical year,(120) Catholics—but those of Eastern Churches according to their own Law (121)—are obliged to attend Mass on that day and on days of precept. (122) It is not advisable therefore to organize ecumenical services on Sundays, and it must be remembered that even when Catholics participate in ecumenical services or in services of other Churches and ecclesial Communities, the obligation of participating at Mass on these days remains.
120 Cf. *SC, *n. 106.
121 Cf. *CCEO, *can. 881, 1; *CIC, *can. 1247.
122 Cf. *CIC, *can. 1247; *CCEO, *can. 881, 1.
vatican.va/roman_curia/pontifical_councils/chrstuni/general-docs/rc_pc_chrstuni_doc_19930325_directory_en.html
CIC is for Latin Church and CCEO is for Eastern Churches, coupled with their particular laws, and also the personal or territorial laws for any of the Churches (see CIC 12 & 13), plus any rescripts published in AAS. But, there are Universal laws in both that overlap, and specific references to Latin or Eastern in both canons so they are not mutually exclusive. And sometimes a lacuna exists, requiring an interpretation, based on the other. (See CCEO 1499 and CIC 17.)
CCEO refers to the Latin Church in these nine canons: 41, 207, 322.1, 432, 696, 830.1, 916.5, 1465. Also sui iuris includes the Latin Church so there are many canons in CCEO that apply to the Latin Church, and general canons requiring all to work together.
The CIC canons that directly bind the Eastern Churches are: 111.1, 112.2, 214, 372.2, 383.2, 450.1, 476, 479.2, 518, 535.2, 846.2, 923, 991, 1015.2, 1021, 1109, 1248.1.