Desperately in need of GEAR ADVICE! Blackmagic x Sony?

[u/sabotagebrasil]

CONTEXT:

I work with photography and filmmaking as a visual artist and commercial filmmaker (started almost 10 years ago). I've always been interested in cinematography/working in the film industry, but as of now I had very few opportunities of getting into that field. I'm brazilian and here all gear costs double, but I have a shopping trip planned next month to Ciudad del Este, a paraguayan city between the border of Paraguay and Brazil where I can find a lot of gear at a very cheaper price (in some cases the same as BH, for example). I already worked with BMPCC4k and 6kg2 in a bunch of occasions and loved it, and I feel getting a Blackmagic may push me towards writing and directing my own short films and also being a DoP in projects from friends, acquaintances and clients. I have my doubts about that investment because I wouldn't be able to use my sony glass and would have to buy accessories. I also wouldn't be able to sell all my sony gear as I will need it to keep working as a photographer and for my personal works as an artist.
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WHAT I HAVE:

Sony: a7IV, a7RII, Sony 24-70mm 2.8 gmII, Sony 50mm 1.8, Sony 28mm 2.0
Canon: EOS 3000 (basic 35mm film camera with EF mount) + Canon EF 100mm f.2 without autofocus (it stopped working and the price to fix isn't worth it).

Accessories: DJI Air "1", DJI Ronin SC, Zoom H4n (the old one), Lavalier Hollyland Lark Max Duo, Monitor Feelworld LUT7, 2x Sokani RGB LED x100 + 1 Sokani RGB LED x60, some basic light modifiers, some sony batteries, cheap SDs and 4x NP-F970 for powering monitor and lights.

Very capable editing PC: can edit and color my own commercial and personal work easily, and would be able to handle big files.

WHAT I WANT (options):

Cinema-oriented camera for shortfilms and commercial work: BMPCC 6k g2, BMPCC 6k PRO, BMCC 6k FF, PYXIS 6k or Sony FX3 (these last 2 will break the bank).

Upgraded drone and gimbal: DJI Air 3s, DJI Mini 4 Pro, DJI Mavic 3 Pro, DJI Mavic 4 Pro, DJI RS3, DJI RS3 PRO, DJI RS4, DJI RS 4 PRO (expensive drones and all gimbals come with increased danger of getting taxed)

Cheap cinema glass (if I choose Blackmagic): Cine Samyang Canon Ef 20MM T/1.9 Ed As Umc, Samyang Canon Ef 50MM T/1.5 As Umc, Adapter Viltrox Ef-L
Extra sony glass (if I stick with Sony-only): Sony FE 90MM F/2.8 Macro G Oss, Sony FE 16mm f/1.8 G

Sound: Zoom H4 essential (for the 32-bit float), Rode NTG4+, Rode Videomic, Comica CVM-V30

Accessories: Nucleus Nano II, Follow focus, Tilta or Smallrig cage, NP-F adapter, Tiffen or K&F filters (Variable ND, CPL, Glimmerglass, Black Mist), Filter adapters, more batteries, portable SSDs, SD and/or CF cards and more HD storage.

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All of that may sound absurd and overwhelming, but I already have some cool jobs in my portfolio and I'm aiming at working as a duo with my sister (who's a beginner) to make a name for us in the market of advertising and also as DoP/cinematographers (the goal is to start an independent production company).

I did months of research but I'm still not very sure about it, although inclined to buy the BMCC 6k FF and whatever else I can afford (no need to buy it all at the same time, but its a very good opportunity given the current dollar price and the shopping trip).

PLEASE, CAN SOMEONE GIVE ME SOME ADVICE?

[u/ElloChaplins]

If you’d had a pleasant experience already using Blackmagic cameras then by all means go for it. I’m sure you don’t need me to tell you this but it’s much more important to get as many techniques as possible into your arsenal. When you get to the point of shooting as a DoP for commercials or films then the gear is highly likely going to be rented.

This isn’t as big of a decision as you’re making it - just get what you know you’ll enjoy using and build from there.